American English

Not only is American English different from British English, but America is so large that there are significant regional differences in American English.

Some of it's accent, which can fairly easily be deciphered. But other differences are colloquialisms used by locals that are harder for outsiders to understand.

For example a Mainer would know that a "dite" is a small amount of something. i.e. "I'll take a dite of ketchup"

When I was a kid in Massachusetts I used to love "frappes." When I moved cross country and tried to order one, no one knew what it was. On the west coast they're milk shakes.

Likewise in a large part of the country long rectangular donuts with a maple frosting are "Long Johns" but in the Pacific Northwest long johns are thermal underwear and those donuts are "Maple Bars"

In the south if someone "fell out" they fainted.

In the east a "crick" is a pain in the neck, but in the west a crick is how they pronounce "creek" (a stream, brook)

In Pennsylvania dutch country to "rid" something is to clean it up and in military culture if you clean something up you "police" it.

For the most part given we all speak English we understand each other pretty well, but somethings do take explaining.