VARIETIES OF ENGLISH
Articles
Differences between British and American English
Differences between British and American English . British Council
Americanisms in British English
Britishisms and the Britishisation of American English
Britishisms 101: An American's Guide to Decoding British English
How Americanisms are Killing the English Language
Grammar
Grammar differences between British and American English
Pronunciation
Simple English Videos Pronunciation Playlist. A collection of 19 videos, most of them devoted to the differences between British and American Pronunciation. Levels A2-C1
Accents of English. Wells. This is a collection of recordings of the same text passage in different accents of English, along with descriptions of the defining features of each accent. The recordings were originally issued in cassettes that accompanied the book by J.C. Wells The Accents of English. Levels C1-C2.
Forvo. This is a dictionary in which you can look up the pronunciation of words in different accents (anyone can record their pronunciation). Any level.