Hold is no different. Lining up sights is lining up sights - and most people use an optic anyway. Triggers differ between different AR’s anyway. The differences you cite would also apply to my AR-15 vs. my AR-10. All are so minor as to be inconsequential.
“Lining up sites is lining up sites” leaves a lot out of even basic familiarization of a platform, never mind developing any kind of proficiency.
Hold is quite different between a pistol grip on an AR and a 10/22 making the trigger pull different. Proper fore end grip is different between the two. Sight radius and sight adjustment are different between to the two, optics for ARs, particularly height and eye distance (generally) are different between the two. Safety, mag release, reload, bolt catch/release are different between the two. None of these apply to the differences between a AR-15 and a AR-10.
Fundamentally all firearms have commonalities, but I’ve sure seen people better with one platform than another. If an AR is going to be a persons primary rifle in a stressful situation then they should develop skills on that platform. Going for a safety/mag release/reload/emergency clear when time is of the essence, that familiarity could make all the difference.