At an all inclusive resort there are usually 3 types of dining options.
A La Carte
Buffet dining will be the most common form of meals for the group. There are many options available each meal and there will often be vegetarian, local and international options. Reservations are generally not required and they have long hours for each meal service ie breakfast from 7 - 10, lunch 11-3 and dinner 5-9
A La Carte options will generally be a specific type of dining with reduced menu (seafood, Italian, Steak house). Not all options will be available each night. Due to the limited seating reservations are normally required. The hotel may limit the number of seatings and the number of reservations allowed per week (ie each guest may reserve 3 meals per week). A dress code may be required. Tipping at these restaurants is encouraged/expected.
Each resort will also have multiple snack bar/grill options. These will usually consist of simple foods such as hot dogs, hamburgers, fries, pizza, fish and chips etc. Normally they are spread out around the property and each will have different hours and days available. There is no additional cost for these and seating is open.
Note: All inclusive means food and drinks are included, but are not typically available 24/7