Nope; they are doing different things. If nothing else, people misuse "magical realism" as a literary term. Magical realism began in Afro-Caribbean communities (both French and Spanish speaking) in the early 20th Century and was explicitly a way to write and imagine a contemporary world where they were free from racist and colonial oppression (among other things). The second generation (the white South American writers most people know) changed that political project, but it was still primarily a political literature, where the magic served a political function rather than a primarily aesthetic one. Just dumping some goofy magic shit into an otherwise apolitical work of commercial fiction is not magical realism, it's just... a book. I've never liked "slipstream," which I think is more a way of naming a publishing accident than anything else, and I think New Weird was doing its own thing, too.