It seems to me that my electric guitar goes out of tuner easier than my acoustic guitar does. Is this because of different string thicknesses on one versus the other? That is, the thicker the string the more prone to stay in tune? That's the only reason I can come up with.
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Could be really any number of things: poor stringing; bridge issues; tuners slipping; different playing; nut problems... there are many things that could cause your tuning to be slipping.
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It could be:

a) Nut isn't filed down enough, which means your strings have a better chance of slipping out of tune and/or producing a really bad sound that you don't want, this could be fixed with filing the gaps where the strings go down a bit more, like in fractions of millimeters, not too much (and only do it if you know this is it or if it's contributing).

b) Cheap or worn down tuners, again, easy fix, give them some tough love and maintenance or just buy new ones.

c) (if your guitar has a FR or anything like it) Poor tremolo bridge setup or extensive whammy-usage

Or your guitar is just a juvenile bad seed.