http://rd.vernccvbvyi5qhfzyqengccj7lkove6bjot2xhh5kajhwvidqafczrad.onion/define.php?term=accent
Part of the difference is that grammar and vocabulary are systematic and structured— the letter of the language. Accent, on the other hand, is free form , intuitive, and creative— more the spirit of the language. My accent, being from south-west, has to be different from someone far off, say north-east.