Firstly, Galaxy and Cadbury chocolate taste different, so a Ripple and a Twirl which are the same type of product are of different tastes, similar to a Cadbury Dairy Milk bar and a Galaxy bar.
But a flake is different, and not just a naked twirl. Different and increased crumbly texture as well as different type of chocolate, you supposedly can not melt a flake, unlike a twirl which you can.
And Flake always had the better adverts when I was a kid.
Flakes were "invented" by a worker picking the accumulated chocolate off the part of a machine where the conveyer belt ended and the chocolate got scraped off at the end.
Twix was invented by a Scottish granny who wrote a letter to Mars saying she melted Mars bars over her shortbread fingers and everyone loved them.
Twirls are superior though, unless you're eating a flake in a bath and the crumb catastrophe can be ignored.