“Appetizers, on the other hand, appear as the first courses when seated at the table.” Dictionary.com
So basically an appetizer is the first served course of a meal and an hors d’oeuvre is a snack served before the meal. And are salads and seafood cocktails considered appetizers? My research says that most times they are.
What about soup? “It might be called an appetizer. A normal portion of soup, though, would come in a larger cup or bowl. Either precedes the main course – unless the soup is the main course. If served in a multi-course meal, soup would come after the appetizer.” Wikipedia
Then Wikipedia says this – which works for me!!!
“A full course dinner is a dinner consisting of multiple dishes, or courses. In its simplest form, it can consist of three or four courses, such as appetizers, fish course, entrée, main course and dessert.”