There are two distinct notions of “sameness” when it comes to objects.

You can test if two references point to the same object ( identity comparison ). This is rarely used; it is mostly useful with large, mutable objects where the object identity matters but the value is transient:

eq? ( obj1 obj2 -- ? )

You can test if two objects are equal in a domain-specific sense, usually by being instances of the same class, and having equal slot values ( value comparison ):

= ( obj1 obj2 -- ? )

A third form of equality is provided by number=. It compares numeric value while disregarding types.

Custom value comparison methods for use with = can be defined on a generic word:

equal? ( obj1 obj2 -- ? )

Utility class:

identity-tuple

An object can be cloned; the clone has distinct identity but equal value:

clone ( obj -- cloned )