First of all, we compare British English with American one.
Source: Baidu
(Continued) Below are minor differences:
BrE: MK Behaviour
AmE: MK Behavior
BrE: Fibre
AmE: Fiber
BrE: oesophagus
AmE: esophagus
BrE: mediaeval
AmE: medieval
BrE: paralyse
AmE: paralyze
BrE: instill
AmE: instil
BrE: fuelling
AmE: fueling
BrE: catalogue
AmE: catalog
BrE: defence (noun)
AmE: defense (noun)
BrE: arguement
AmE: argument
BrE: cheque
AmE: check
BrE: minigramme
AmE: minigram
As to the pronuncation difference,
use "douchebag" as a prologue.
In cultural sense:
BrE: water closet
AmE: john (NOT John)
BrE: bathroom
AmE: restroom
BrE: condom
AmE: rubber
BrE: school (schoo)
AmE: school (scho-ol)
Note: American are far less hypocritical compare to Britain.
48 Things British People Say And What They Actually Mean - AngMohDan