Alternate Reality stories are those that do not acknowledge the entire Total Drama canon as it existed when the author started writing the story (or predecessor story, in the case of sequels), but it still exists in the Total Drama multiverse. Competition stories of this type are usually reimaginings, rebuilding an entire canon season from the ground up. Noncompetition alternate-reality stories most often rest on the premise that Total Drama Island never happened at all, in which case the author is mainly using Total Drama canon characters for their prepackaged personality traits.
The What If story, which speculates on what would have happened if a single incident had played out differently than it did in the canon version, is a subtype. "What If" stories are usually noncompetition stories, and acknowledge all canon events prior to the incident that the story is based on.