【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).