Re: He speaks with a Tennessee accent.
A personal note. I consider major dialect/accent groups such as American English (which I would prefer to call US English - Canadian English is different), what is generally known as British English (which would perhaps be better named Standard Southern English English), Scottish English, Irish English etc to be varieties of English. Within each variety there many be many dialects and sub-dialects.
Varieties/dialects differ from each other in any or all of lexis, grammar, pronunciation of phonemes, intonation, etc.
People who speak using the same grammar and lexis, but pronounce one or more of the phonemes in a different way, and/or use different stress/intonation patterns have different accents.
Informally, many people use the word accent when phoneticians would use dialect/variety.
Note that some dialects/varieties have phonemes that do not exist in other dialects/varieies, for example the sounds in Scottish loch, Irish lough, Welsh Llanelli.
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