Claude Opus 4.5 vs Composer 2

Pick Claude Opus 4.5 if you want the stronger benchmark profile. Composer 2 only becomes the better choice if you want the cheaper token bill or you want the stronger reasoning-first profile.

Claude Opus 4.5 is clearly ahead on the provisional aggregate, 77 to 73. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Opus 4.5's sharpest advantage is in coding, where it averages 65.9 against 58. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 59.3% to 61.7%.

Claude Opus 4.5 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $0.50 input / $2.50 output per 1M tokens for Composer 2. That is roughly 10.0x on output cost alone. Composer 2 is the reasoning model in the pair, while Claude Opus 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.