The platters are presented to the guests and the guests pass and serve themselves. This requires more space and service can be slow. Family Style is when the food is in bowls and on platters in the middle of the table and the quests help themselves. Buffet style is when the people stand in a food line. The staff may wear tuxedo shirts with bow ties and blank pants or skirts.
Butler style is when the waitpersons where white gloves.
If you are having a Hawaiian theme party, ask your caterer to have the wait staff where Hawaiian shirts. Generally, there should be at least one server per 30 guests for a buffet and one server per 20 guests for a sit-down dinner. However, it depends on how formal or complicated the event is. The ratio may be reduced, depending on these factors. Discuss the staff to guest ratio with your caterer.