GPT-3.5 Turbo vs Gemini 2.5 Pro (I/O Edition)

Compare GPT-3.5 Turbo by OpenAI against Gemini 2.5 Pro (I/O Edition) by Google AI, tested across 18 shared challenges. Updated April 2026.

Which is better, GPT-3.5 Turbo or Gemini 2.5 Pro (I/O Edition)?

GPT-3.5 Turbo and Gemini 2.5 Pro (I/O Edition) are both competitive models. GPT-3.5 Turbo costs $1.5/M input tokens vs $1.25/M for Gemini 2.5 Pro (I/O Edition). Compare their real outputs side by side below.

Key Differences Between GPT-3.5 Turbo and Gemini 2.5 Pro (I/O Edition)

GPT-3.5 Turbo is made by openai while Gemini 2.5 Pro (I/O Edition) is from google. On pricing, GPT-3.5 Turbo costs $1.5/M input tokens vs $1.25/M for Gemini 2.5 Pro (I/O Edition).

Our Verdict
Gemini 2.5 Pro (I/O Edition)
Gemini 2.5 Pro (I/O Edition)
GPT-3.5 Turbo
GPT-3.5 TurboRunner-up

No community votes yet. On paper, Gemini 2.5 Pro (I/O Edition) has the edge — bigger model tier, newer.

GPT-3.5 Turbo is 5.0x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
83%

Gemini 2.5 Pro (I/O Edition) uses 578.2x more bold

GPT-3.5 Turbo
Gemini 2.5 Pro (I/O Edition)
61%Vocabulary58%
16wSentence Length16w
0.23Hedging0.38
0.0Bold5.8
3.7Lists5.0
0.00Emoji0.00
0.00Headings0.63
0.38Transitions0.01
Based on 11 + 16 text responses
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GPT-3.5 TurboGemini 2.5 Pro (I/O Edition)

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
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