So many usages that were once confined to one side of the pond or the other have now become common on both sides. Much of what is posted above as British or American falls apart when regionalisms are taken into account.
Also usage has changed with time; when I was a child, vest in the U. S. meant an undershirt as well as a waistcoat, now it has become a waistcoat- but one that matches the pants (tailors prefer trousers) and suitcoat. Fancy waistcoats are worn primarily as period pieces.

Color was originally Latin; which now is couleur in French but remains color in Spanish; the English colour (colur) became usual in England in the 14th c., but color also was used in the 15th c and later, becoming standard in the U. S. Color predates Webster in the U. S., he just accepted general usage. Why? Dunno. In fakelore books, it is said that the 'u' distinguishes words borrowed from the French, but this is not true- the 'u' is applied to some words that did not come from French, and is left out of others.

Webster was a standardizer, but there were several compilers in the British Isles who accomplished standardization as well.

Much of what is being posted here has been gone over in several earlier threads. The subject seems to come up in about a nine-month cycle.