the psychology of Gray/Grey

[RonButters at AOL.COM]

I can understand how GREASE&GREASY could come to mean two different things to
people such as Dennis Preston, given that GREASE&GREASY can have two
different pronunciations (i.e., with /z/ or /s/).

But GREY and GRAY? I guess this must be some kind of back formation on the
analogy of such homophones as TAIL and TALE (or PAIR, PEAR, and PARE), but
the inference that the difference between a spelled E and a spelled A would
signal a difference in SHADE of grey/gray strikes me as counterintuitive.
Would one infer that COLOR&COLOUR have slightly different meanings, or
THEATRE&THEATER?? Are there any other alternate spellings in which the
semantic difference is one of degree rather than kind? Some spellings MAY BE
fancy and some plain, but connotatively, not denotatively.

By the way, my AOL spellchecker rejects GREY entirely.