I'm not big into definitions or trying to constrain design to set terminology. But terms are useful in conveying ideas and communicating your design (mime just won't cut it for mechanical martini shakers). Two big words which are commonly viewed as interchangable are pass and fail but these are quite different. Two other words are equivalent and alternative. While alternative tends to be more easily understood. It is equivalence which is seen to be equivalent to the other (see what I did there - no you didn't. You read it.). 

Hosted by coming to an equivalent solution alternatively by M.Boer and S.Schekman on 13 July 2021