10 Differences between American spelling vs. British spelling.

American spelling:
As we mentioned in ( Which version of English are you learning/ speaking?) There are visible differences between American English & British English in both grammar & vocabulary. The differences in vocabulary are either in that each use a completely different word or they write / pronounce it differently.
This is a list for words that are only spelled differently.
Check list of differences in vocabulary for words that are completely different.
(Note: AmE = American English. BrE = British English)
American spelling        vs.           British spelling

1. Most ‘-our’ patterns in British English is ‘-or’ in American English. As in;

color                          colour
armor                        armour
favorite                     favourite
flavor                        flavour
humor                      humour
harbor                      harbour
rumor                       rumour
2,Words that end in ‘-Log’ in American English is ‘-logue’ in British. As in;
catalog                      catalogue
dialog                        dialogue
analog                       analogue

3. Verbs that end in ‘-el’ have their past tense/ continuous tense in ‘-elled’/’-ing’ in British English & ‘-eled’/’-ing’ in American English. As in;

canceled                cancelled

traveled                  travelled
traveling                 travelling
Exception:  To expel (in both AmE & BrE = expelled).

4. Some words other than verbs (nouns, adjectives)
that have ‘-el’ or ‘-al’ in American English, have ‘-ell-‘
or ‘-all-‘ in British English;

counselor              counsellor

signaling                signalling

woolen                  woollen

5. ‘-ize’ in American English is ‘-ise’. As in;

recognize                 recognise

Emphasize               emphasise
modernize               modernise

6. ‘-yze’ in American English is ‘-yse’ in british English. As in;

analyze                   analyse

catalyze                  catalyse

paralyze                 paralyse

7. ‘-er’ at the end of some words In AmE are ‘-re’ in British English;

theater                     theatre
kilometer                 kilometer

8. Some word with ‘-ae-‘ in them in BrE are written with only ‘-e’ in AmE;
anesthesia              anaesthesia
anaemia                  anemia

9. Most words that end in ‘-se’ in American English  are written ‘-ce’ in BrE:

defense                   defence

offense                   offence
License                    licence
pretense                 pretence

(Exception: US to practice = UK to practise.)

10. Miscellaneous differences:

to bathe                    to bath
tire                            tyre
program                  programme
disk                          disc

Note: There are sometimes differences in some past tenses of some verbs.
AmE spell     spelled          spelled
BrE   spell     spelt              spelt
AmE   smell       smelled     smelled
BrE     smell       smelt        smelt
(See list of irregular verbs)