Is the AI Writing Report the Same as the Similarity Report?
Table of Contents
- What Is the Difference Between a Turnitin AI Writing Report and a Similarity Report?
- How Does Turnitin Determine Whether Content Was AI-Generated in the AI Writing Report?
- Can Students Check Their Own Turnitin AI Writing and Similarity Reports Before Submitting?
- FAQ
- Sources
- Related articles
Direct Answer - No, the AI Writing Report and the Similarity Report are two separate, independent reports within Turnitin that measure entirely different dimensions of a submission. The AI Writing Report detects text that may have been generated by an AI tool, whereas the Similarity Report identifies text matches against Turnitin's extensive database of published works, web content, and previously submitted student papers. Both reports serve distinct but complementary roles in academic integrity assessment, and instructors view them side by side in Turnitin Feedback Studio [1].
What Is the Difference Between a Turnitin AI Writing Report and a Similarity Report?
The core difference lies in what each report measures. Turnitin's AI Writing Report analyzes the submitted text itself to determine what percentage of qualifying prose appears to have been generated by a large language model (LLM) or modified by an AI-paraphrasing tool. The report displays an overall percentage, detailed in two detection categories: AI-generated only (highlighted in cyan) and AI-generated text that was AI-paraphrased (highlighted in purple) [2].
The Similarity Report, by contrast, does not analyze the origin of the writing. Instead, it compares the text against Turnitin's continuously updated database of web pages, academic journals, books, and student papers submitted to Turnitin worldwide. It produces a similarity percentage and highlights passages that match existing sources, helping instructors identify potential plagiarism or improper citation.
The percentage generated by Turnitin's AI writing detection model is fundamentally different from and independent of the similarity score. Importantly, AI writing highlights are not visible within the Similarity Report itself; instructors must access the dedicated AI Writing Report to view flagged sentences [2]. A submission could have a high AI writing score with a low similarity score (original but AI-generated content) or a high similarity score with a low AI score (human-written but poorly cited content).
How Does Turnitin Determine Whether Content Was AI-Generated in the AI Writing Report?
Turnitin's AI writing detection model is trained on a massive dataset comprising millions of academic papers and AI-generated texts from various large language models, including GPT-4, Claude, Gemini, and others. The model analyzes each sentence within a submission for statistical patterns characteristic of AI-generated text, such as uniformity in sentence structure, predictable word choices, and lack of the natural variability found in human writing [3].
Specifically, the model evaluates two key linguistic dimensions: perplexity (how predictable a text is for the model) and burstiness (the natural variation in sentence length and complexity that typically characterizes human writing). AI-generated text tends to exhibit lower perplexity and more uniform burstiness compared to human-written prose. Turnitin's model breaks detected text into two categories: "AI-generated only" for text likely produced directly by an LLM, and "AI-generated and AI-paraphrased" for text that was originally AI-generated and then modified using a paraphrasing tool like Quillbot [2].
Importantly, the model only analyzes qualifying text — prose sentences in a long-form writing format — and its detection methodology has been refined through continuous testing against known AI-generated samples [3]. It does not reliably detect AI-generated text in non-prose formats such as poetry, scripts, code, bullet points, tables, or annotated bibliographies. Additionally, for English-language submissions, the detection includes AI paraphrasing and AI bypasser detection capabilities, while the Spanish and Japanese detectors currently do not [2].
Can Students Check Their Own Turnitin AI Writing and Similarity Reports Before Submitting?
Under standard institutional settings, students cannot independently view either the AI Writing Report or the Similarity Report before submitting their work to an official assignment. The AI Writing Report is generated only after a submission is processed through an instructor-created assignment, and its visibility depends entirely on the instructor's account configuration and institutional policies [4].
For the Similarity Report, options are limited. If a student's institution provides Turnitin Draft Coach, they can run similarity checks, citation checks, and grammar checks within Google Docs or Microsoft Word before final submission. Without Draft Coach, students can only check similarity by submitting drafts to assignments that permit resubmissions — though resubmission limits (typically three within 24 hours for new standard assignments) and 24-hour waiting periods for subsequent reports apply [4].
This restricted access creates a practical challenge for students who want to proactively verify their work before a final graded submission. Many students turn to external checking services that can generate both Turnitin AI writing and similarity reports independently, allowing them to preview their scores and make necessary revisions before submitting to their instructor.
Understanding the difference between these two reports is the first step — but knowing your own scores before submission can save you from unpleasant surprises. With Turnitin0's checking service, you can upload your document and receive both the AI Writing Report and the Similarity Report that match exactly what your instructor sees in Turnitin Feedback Studio. No subscriptions, no archival of your papers — just clear, actionable results delivered within minutes so you can revise with confidence.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
FAQ
1. Can a paper have a high AI score but a low similarity score?
Yes. A paper written entirely by AI but containing no copied or matched text from existing sources would show a high AI writing percentage alongside a very low similarity percentage. This is why instructors review both reports together before making any academic integrity determination [1].
2. What does the asterisk (*%) mean on the AI Writing Report?
When the AI detection score falls between 1% and 19%, Turnitin displays an asterisk (*%) instead of a specific numeric percentage. This is because testing has shown a higher incidence of false positives in this range, and the asterisk signals that the score should be interpreted with caution [2].
3. Does the Similarity Report also detect AI writing?
No. The Similarity Report only identifies text matches against Turnitin's database of existing sources. It does not analyze whether text was AI-generated. AI writing highlights are not visible within the Similarity Report; they appear solely in the dedicated AI Writing Report [2].
4. How accurate is Turnitin's AI detection model according to published research?
Turnitin states that its AI detection model was trained on millions of academic and AI-generated texts and has been validated through ongoing testing. However, the company also notes that false positives (incorrectly flagging human-written text as AI-generated) remain a possibility, which is why the report should not be used as the sole basis for academic decisions [3].
5. How long does it take for the AI Writing Report to generate after submission?
The AI Writing Report generates within minutes for most submissions, provided the file meets the requirements (at least 300 words of prose text, under 100 MB, supported file types including.docx,.pdf,.txt, and.rtf). In rare cases, processing may take longer, and the report will display a "Loading" state until complete [2].
Sources
- Turnitin AI Writing Detection FAQs — https://guides.turnitin.com/hc/en-us/articles/28477544839821-AI-Writing-Detection-FAQs
- Using the AI Writing Report — https://guides.turnitin.com/hc/en-us/articles/22774058814093-Using-the-AI-Writing-Report
- AI Detection Explained: What Educators Need to Know — https://www.turnitin.com/blog/ai-detection-explained-what-educators-need-to-know
- Can Students Check a Paper in Turnitin for Similarity Before Submitting? — https://helpcenter.turnitin.com/hc/en-us/articles/27811948436237-Can-students-check-AI-writing-and-similarity-before-submitting