I read somewhere, a while back, that Oxygene was the song of 'air' and Equinoxe was the song of 'water'.
I think that person made quite an interesting and worthwhile description.
Take for example Oxygene, the first track he did on that is O2, and that track is filled with all kinds of white noise sfx. O1 and O3 don't have any, but O4, O5 and O6 definitely do - more white noise. That was the common element throughout the album, and Jarre played to that very much. Other contemporaries at the time did much the same, just not so much in an orchestral way, as Jarre. More in a soundscape-y 'look what I can do' kind a way.
Schulze's Timewind came out just the year before, and that album surely had an enormous influence on Jarre, in helping further shape that specific type of fantastic/sci-fi electronic music, which pervaded the time.
Take all that and combine with what Jarre was wanting to do at the time, create more accessible electronic music, by combining pop music with experimental EM, and you have a wonderful fusion of elements coming together.
And lastly Jarre was into environmentalism.
So you get experimental sound design and classica & jazz melodies.
So it's not just one thing that influences a name of a track, or an album, although that does happen very often, I find that when a number of interests and fields coverge, that often makes for a much more interesting and satisfying reason for giving something that specific name.
On Equinoxe, many of the sounds that come from his VCS3/AKS are very 'watery', both literally and sometimes in an abstract manner. E2, E3, E4, E5, E7, E8.
Without faith nothing is possible. With it, nothing is impossible.
