U's please, we're British

Bringing up Scrabble again.  One thing good players learn is that the British sometimes spell the same words differently than Americans.  Bonus: both versions are valid in Scrabble and in SpellTower.  The most common is the -or vs. -our ending:  color/colour, valor/valour, favor/favour, etc.  In this case, I'm going to side with Albion, since their words have an extra letter and, hence, produce more points.

Some other British words that differ from American ones are curb/kerb and jail/gaol.  There are certainly others, but I'm going by a faulty memory here.  Any other suggestions?  [Update on 29-Apr]: I forgot about the -er vs. -re endings: center/centre, liter/liter, etc.  These are often lifesavers in SpellTower.

Finally, a very clever poem by G.K. Chesterton that deflated the notion that Americans are terser than their UK counterparts: A Ballad Of Abbreviations.