User blog comment:OverlordRocks/Who got rid of the cave realm page?!!!!!!!!!!!!!!!!!/@comment-27507964-20160126233711

There are actually two different types of portals. The main difference seems to be what season you are in. There is one type of portal for the pilots and seasons 1 and 2 and there is a separate type for seasons 4, 5, and 6. (There are no portals in season 3.) I thought here might be some portals for travel in the same dimension and travel to other dimensions but it turns out there isn't.