noun
A and B; first and second
Used when labeling or comparing two items, options, or parties, often in formal or legal contexts. Common in phrases like 甲乙つけがたい (hard to choose between the two).
両者の実力は甲乙つけがたい。
It is hard to say which of the two is better.
契約書には甲乙双方の署名が
The contract requires signatures from both Party A and Party B.
noun
difference in quality; superiority or inferiority
Refers to a discernible gap in quality, rank, or merit between two things. Often used in negative constructions to say there is no significant difference.
この二つの案に甲乙はない。
There is no difference in quality between these two proposals.
性能に甲乙があるなら、高い方を選ぶ。
If there is a difference in performance, I'll choose the better one.