Catering is a speciality within the food industry.
In general, a restaurant cooks the food on the premises and serves it a few minutes later.
In general, a catering business cooks the food in their kitchen, and transports it to the event site. Given the event size (20 to 1000 people), some food is cooked a day or more in advance and stored, and some food is cooked the day of the event. On the day of the event, the food and the serving dishes are transported to the event site. The travel time and serving time may be one to three hours.
So, a catering business has more food safety challenges than a restaurant.