Full Idea
'The wolves' is a plural term referring to just these animals, whereas 'the pack' of wolves refers to a group, and the group and plurality, while they may coincide in membership, have different identity conditions. The wolves are the matter of the pack.
Gist of Idea
'The wolves' are the matter of 'the pack'; the latter is a group, with different identity conditions
Source
Peter Simons (Parts [1987], 6.4)
Book Reference
Simons,Peter: 'Parts: a Study in Ontology' [OUP 1987], p.234
A Reaction
Even a cautious philosopher like Simons is ready to make bold ontological commitment to 'packs', on the basis of something called 'identity conditions'. I think it is just verbal. You can qualify 'the wolves' and 'the pack' to make them identical.