Common Differences between British and American English

-re / er

Words that end in -re in British English usually end -er in American English:
British: centre
American: center

-our / -or

Words that end in -our in British English often end in -or in American English:
British: colour
American: color

-ise / -ize

-ise verbs are always spelled with -ize in American English:
British: organise
American: organize

-yse / -yze

-yse verbs are always spelled -yze in American English:
British: analyse
American: analyze

ll / l

In British English, the l is doubled for verbs ending in a vowel plus l. In American English, the l is not doubled:
British: travelled
American: traveled

-ence / -ense

-ence nouns in British English are spelled -ense in American English:
British: defence
American: defense

British vs American English: 10 Words

British	American
Sweets	Candy
Shop	Store
Trousers	Pants
Timetable	Schedule
Petrol	Gas/Gasoline
Holiday	Vacation
Flat	Apartment
Pavement	Sidewalk
Maths	Math
Cinema	Movies