i’d also say the difference between “dancehall with typical Raggae off beat cords and laid back attitude”
“that merengue based push forward stuff is one genre?”
is about forty years. Dancehall started as an offshoot of reggae that just removed the original vocals and had someone chatting over it, then became it’s own thing, then mutated around the 1990s to become it’s own distinct sound, pretty much losing the offbeat chords from reggae (though not always!).
It’s since borrowed a lot from a lot of places including Indian music, US hip hop and basically anything a JA producer found useful. That 3+3+2 beat was pretty central through the 90s and 00s, with Dembow as the other flavour (mostly) but I’d say in the 2010s and 2020s Dancehall has if anything become even more global looking such that it’s borrowing stuff from all over, probably including taking sounds back from reggaeton, which essentially started from doing the same to dancehall in the first place.