From Liquipedia Warcraft Wiki
In this Portal you can find all the information you need about Warcraft III Tournaments.
Team Tournaments (2 player teams excluded)
have not precise features. A group of players can represent a country, a team
or a race. It can aslo be an ad-hoc team. There is usually between three and ten player in a team, matches can be 1v1, 2v2 in different format. Here you can find 3v3 and 4v4 tournaments too.
Qualifier team tournaments
Qualifiers are tournaments where there are little to no prize money, and the main goal for the teams is to be qualified for a bigger event.