Claude Opus 4.8 vs union-alpha
Wins 2 of 4 areas
Reasoning · Following instructions
Wins 2 of 4 areas
Coding · Math
The two are evenly matched.Claude Opus 4.8 is better at reasoning and following instructions; union-alpha at coding and math.
Scores updated · 7 tests both models report · How we compare
Where each one wins
Tests won in each of the four areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
Reasoning, math and following instructions rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Opus 4.8 pulls ahead
- Follows detailed instructions exactlyLiveBench · Instruction Following+12.5points ahead
- Fresh logic puzzles that change regularlyLiveBench · Reasoning+8.4points ahead
Where union-alpha pulls ahead
- Fixes real GitHub issues, working as an agentLiveBench · Agentic Coding+4.2points ahead
- Fresh competition math problemsLiveBench · Mathematics+1points ahead
Every test, side by side
All 7 tests both models report. The winning score is in its model's colour; marks a score checked independently.
Codingunion-alpha
- LiveBench · Agentic Codingunion-alpha by 4.250.554.7+4.2
- LiveBench · Codingtie81.882.2tie
ReasoningClaude Opus 4.8
- LiveBench · ReasoningClaude Opus 4.8 by 8.489.280.8+8.4
Following instructionsClaude Opus 4.8
- LiveBench · Instruction FollowingClaude Opus 4.8 by 12.57259.5+12.5
Other results2 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- livebench_data_analysisunion-alpha by 8.66674.6+8.6
- livebench_languageunion-alpha by 6.279.785.9+6.2
Questions people ask
Which is better, Claude Opus 4.8 or union-alpha?
Claude Opus 4.8 and union-alpha each win two of the four areas where both have results. Claude Opus 4.8 wins reasoning and following instructions; union-alpha wins coding and math.
Which is better for coding?
union-alpha. It wins 1 of the 2 coding tests both models report; Claude Opus 4.8 wins none, and 1 is a tie.
How do you compare the two?
We use the 7 benchmark tests both models have published scores on. The verdict counts the 5 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 2 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.