A Food Service Establisment is defined as the following:
A food service establishment is a place where food is prepared and intended for individual portion service and includes the site at which the individual portions are provided, whether consumption occurs on or off the premises. The term excludes food processing establishments, retail food stores, private homes where food is prepared or served for family consumption, and food service operations where a distinct group mutually provides, prepares, serves and consumes the food such as a “covered-dish supper” limited to a congregation, club or fraternal organization.
A caterer is a person who prepares, furnishes, or prepares and furnishes food intended for individual portion service at the premises of the consumer, whether such premises are temporary or permanent. A caterer is considered a food service establishment operator and is required to operate in conformance with this Subpart.
The most up-to-date New York State Environmental Health regulations can be found at the following site.