If you recruit members through a member group (e.g. employees of a company), the membership type(s) for these can be marked as such. This then lets you:
relate the group member to the group of which they are part, by setting the membership number of the group within the member record
locate all the members who are in that particular group (according to that field). This is done using the existing cross-reference search in Search More – Miscellaneous Queries (which previously only applied to cross-referenced custom fields).