The Halloween franchise is somewhat unique among slasher movies in that it has numerous continuities. All of the movies take place after the 1978 original, though not all of them are canon with each other. Thus, it can be confusing to keep track of which movies are related to one another, especially when some of them were released in such quick succession. Such is the case with a somewhat infamous sequel from 2002.
Source：https://www.cbr.com/halloween-resurrection-h20-sequel/
