GPT-6・Sonnet 5.5・Opus 5.5・Gemini 3…どれを使えばいい？2026年10月版AIモデル選定の完全ガイド

Sat, 10 Oct 2026 12:00:00 +0900

「ChatGPTのGPT-6って、Sonnet 5.5と何が違うの？」

先日、エンジニアの同僚から聞かれてとっさに答えられなかった。「なんか賢いやつ」では回答にならない。

GPT-6, Sonnet 5.5, Opus 5.5, Gemini 3 — Which AI Model Should You Use? The October 2026 Complete Selection Guide

Sat, 10 Oct 2026 12:00:00 +0900

“Wait — what’s the difference between ChatGPT’s GPT-6 and Claude’s Sonnet 5.5?”

A colleague asked me this the other day, and I couldn’t answer on the spot. “It’s the smarter one” doesn’t cut it as an explanation.

AI is evolving so fast that each company now offers multiple models simultaneously. OpenAI has rebuilt its lineup into a three-tier GPT-6 family (Astra, Sol, Luna). Anthropic now spans four tiers with Fable, Opus, Sonnet, and Haiku. Google splits between Pro and Flash. Model names have nearly been swapped out wholesale since I first wrote this article six months ago. Before you can even “use AI,” you’re stuck deciding which model to use — and that decision keeps getting harder, not easier.

GPT-6 on firebirdテックトーク

GPT-6・Sonnet 5.5・Opus 5.5・Gemini 3…どれを使えばいい？2026年10月版AIモデル選定の完全ガイド

GPT-6, Sonnet 5.5, Opus 5.5, Gemini 3 — Which AI Model Should You Use? The October 2026 Complete Selection Guide