Science Fiction and Fantasy is the same thing for these purposes. Any significantly advanced technology is indistinguishable from magic. Children meaning pre- pubescent. Many Disney films qualify (Pinnochio, Bambi). E.T. sort of updated the Disney template for the post Walt age.
No, not the same. ET as fantasy is not the same as ET as science fiction.
If the latter, ET is real. As fantasy, his reality is beside the point.
As fantasy, it is very dark and adult.
As science fiction it makes more sense.