How can you tell the difference between a major and a weekly?
Tournament type designations are more like clusters than rigid categories, but these two are far enough apart that it's easy to generalize. One occurs (close to) every week, is of variable size (though generally <100 people), and usually features the same pool of players. The other occurs infrequently, is very large (often >200 players), and attracts talent from all around the country. There are other designations (ex. regional) that fall between these extremes, and this is where the lines get blurrier.