Final answer:
A tongue flap creates pronounced differences between American and British English in words with medial 't' such as 'water,' where Americans might use a 'd' sound and Brits articulate the 't' more clearly.
Step-by-step explanation:
The group of words where a tongue flap creates significant differences between American and British pronunciations typically involves words with a medial 't,' as in 'water' where Americans might use a 'd' sound (wader), and Brits will enunciate the 't' more clearly.
This difference is also notable in words where the 't' occurs in consonant clusters, such as 'party,' where it is pronounced more like 'pardee' in American English and 'pahty' in British English.
Differences in pronunciation extend to other areas as well, such as the additional 'u' in British English spellings like 'colour' and 'flavour' versus the American 'color' and 'flavor.'
However, it's important to note that within both American and British English, there are numerous regional accents and dialects that can have their own unique rules regarding pronunciation, vocabulary, and even grammar.