In the smartphone OS market, it doesn't matter if apple is on the luxury spectrum and android is on the general spectrum, because they are the only relevant OSs around (excluding harmony because it doesn't have nearly as much market share as those two).
So yes, android and iOS are competitors, unless other luxury OS pops up to compete with iOS or OSs like harmony become more relevant to compete with android.
If Kia and RR were the only car brands, they'd be competitors of each other because there are "cheap" second hand cars by RR that compete with Kia (like second hand iPhones) and expensive Kia cars that compete with RR (expensive android phones that compete with apple ones).