The best summary of Scots variations I know is in David Crystal's 'The English Language'. Too much detail to post here. He distinguishes between Scots, Lallans and Lowland Scots. Some lexical features are shared with dialects from the North of England. A great deal of the distinctiveness of the 'Scots lexicon' derives from the influences of other languages especially Gaelic, Norwegian and French. But its origins like those of English are with invaders from Europe who also brought

(The original 'Scots' were, of course, Irish.)


Crystal has a map of Scots dialect areas, and the western bit within which Burns grew up (Ayrshire) seems to be on the border of the west central and sw central areas. So not the bit of modern Scotland that was in the old Angle kingdom of Northumbria.

Interestingly, Crystal describes 'Lallans' as a synthetic mainstream Scots created in the 20th century, something that emerged first of all in poetry rather than speech.