What a cool idea for a thread, Lynn! I've always been interested in this topic. (Although, the more I'm able to discriminate between the two, the more I wonder which one to use while writing laugh )

My list: ( laugh )

First of all, the easy one:
Spelling issues:
UK behaviour vs. US behavior, UK theatre vs. US theater UK travelling vs. US traveling and so on.

Queue vs. line:

UK version: "The queue for the roller-coaster was very long."
US version: "The line for the roller-coaster was very long."

The period:

UK Dr vs. US Dr., UK Mr vs. US Mr. etc..

Also, there are some things I have seen and I don't know if they're UK vs. US differences, or it's just wrong phrasing I happened to see. Maybe someone could clarify them.

1) "Who are these flowers for?"
vs.
"For whom are these flowers?" or "These flowers are for whom?"

2) Spelling issues like dreamt/dreamed or learnt/learned.

I'm sure there are others, but I'm probably to sleepy to remember laugh

See ya,
AnnaBtG. (non-native English speaker, please be gentle peep )

What we've got here is failure to communicate...