Sociolinguistics 2, Exercise 1: accent, dialect, idiolect

A pronunciation difference only      accent (in general, accent covers pronunciation)
A difference in grammar, vocabulary  dialect (dialects differ in phonology,
and pronunciation shared by a        morphology, syntax and vocabulary)
region
The way one person speaks            idiolect (one individual's variety)

Source: Wikipedia, Dialect. John Lyons notes that many linguists treat accent
differences as part of dialect differences, so the boundary is not sharp.