I've been watching a podcast lately which features a country guitarist and a blues guitarist discussing various aspects of guitar-craft. When comparing stylistic differences, the blues guitarist often says to the country guitarist something akin to...
that's because you are playing over the changes
I've seen questions on here about playing over the changes but I'm a little unsure as to exactly what they mean.
So, specifically, what is 'playing over the changes'? What are the stylistic implications for country and blues, and more generally in other styles like jazz and rock?