Right, actually none of these are X/Y. X/Y means coincident in the horizontal plane, with no arrival-time differences between channels, regardless of what direction the sound is coming from. This requires the centers of the two capsules to fall along a common, vertical line. Thus even microphones "touching heads" at their outside corners isn't X/Y.
The directional pattern of the microphones or the angle between their main axes isn't part of the definition; only the coincident placement (with the consequent effect on arrival time) is. In that sense, M/S is legitimately a kind of X/Y.
90 degrees is actually a pretty crappy choice for music recording with cardioids. Cardioid isn't a sharply directional pattern, so at 90 degrees the majority of the sound energy which the two capsules pick up will be identical, resulting in a near-mono recording. A 90-degree cardioid arrangement can be useful for business recording (e.g. meetings in an office, where people are sitting all around a table and everyone is relatively close to the recorder), but for music recording at moderate distances, you need the mikes angled farther apart and/or with greater directivity, or else you're pretty much missing the boat with the whole stereo thing.
--best regards