What’s the difference between a dialect and an accent?

An accent is a very constrained form of variation. It only affects the pronunciation (i.e. phonetics and phonology) of a speaker. While a speaker of RP (Received Pronunciation) in the South of England (e.g. the Queen) and a speaker of SSE (Scottish Standard English) in Edinburgh (e.g. First Minister Nicola Sturgeon) may pronounce words very differently, they still use the same syntax, lexical items and morphology.Dialects, on the other hand, vary from the Standard on multiple linguistic levels. Scots, the dialect spoken in Lowland Scotland (Glasgow, Perth, Edinburgh etc, uses different phonetics and phonology than Standard English (e.g. rhotic /r/), but also different vocabulary (think of Aye, Nay, wee, nooks and crannies etc) and syntax (there is a plural form yous for the second person).Note that there is no clear consensus where a dialect ends and a language begins so Scots is sometimes also characterised as a language.