Full Idea
Composition as identity claims that a single object is identical with the many parts it comprises; constitution as identity says that a single object (a statue) is identical with a single object (clay) that 'constitutes' it.
Gist of Idea
'Composition' says things are their parts; 'constitution' says a whole substance is an object
Source
Trenton Merricks (Objects and Persons [2003], §1 n11)
Book Reference
Merricks,Trenton: 'Objects and Persons' [OUP 2003], p.20
A Reaction
The constitution view has been utilised (by Lynn Rudder Baker) to give an account of personal identity as constituted by a human body. Neither sounds quite right to me; the former view misses something about reality; the latter doesn't explain much.