difference between and individual C.a and asoociates

A firm with name XYZ & co. Indicates that the firm is a partnership firm where the partners jointly carry on their professional engagement from same place of business and sign on behalf of the firm.

Whereas, when the name is XYZ & Associates, it indicates that different professionals and practioners draw business from the market in the name of XYZ & Associates but engage in the project in their individual name and sign in an individual capacity & may have different place of work than XYZ. It is like a cartel of smaller firms to compete with the bigger partnership firms.

Hope its clear :)