This paper offers a contrastive analysis of the identifiers same and mismo. It begins with a discussion of the morphologjcal and distributional features that characterize them and distinguish one from the other. The Spanish adjective has more flexibility of distribution than the English one. The notion of identification is carefully explained, defined and differentiated from that of equality or likeness. Same and mismo are the terms mostly used to express the idea of identification and, therefore, they are syntactically and semantically analysed in detail. They are compared with words of similar meaning such as like/como, equal/igual, idéntica!/idéntico and distinguished from them. Finally, the nominalization of the two adjectives, same and mismo, is also discussed and contrasted. The greatest difference between the two substantivized identifiers are found not at the level of meaning but at the level of morphology.