Same, selfsame, very, identical, identic, equivalent, equal, tantamount can mean either not different from the other or others or not differing from each other.
Same may imply, and selfsame invariably implies, that the things under consideration are in reality one and not two or three different things.
But same may also be applied to things actually distinct but with no appreciable difference in quality, kind, appearance, amount, or significance.
Very, like selfsame, implies complete absence of difference and therefore oneness in the things under consideration.
Identical (see also LIKE ) implies either selfsameness <I found it at the identical spot where I left it> <the authors of the anonymous Waverley and of the popular Lady of the Lake were found to be identical > or absolute agreement in all details (as of quality, shape, and appearance).
Identic occurs chiefly in diplomatic or governmental use and like identical implies absolute agreement in all details.
Equivalent is used of things that amount to the same thing or are freely interchangeable in some respect (as worth, force, significance, or import).
Equal implies complete correspondence (as in number, amount, magnitude, or value) and therefore equivalence but not selfsameness.
Tantamount, otherwise identical with equivalent, is restricted in application to one of a pair of usually immaterial things that are in effect equivalent the one to the other (as in value, significance, or effect).