Not as noticeable as if you bought a Gibson Les Paul ;-)
Both guitars are aiming for the strat vibe so they're trying for the same sound. The more expensive instrument _should_ carry you there in more style. It _should_ feel smoother, more alive, easier to play but... that isn't guarranteed. There's alot of variation in the Fender mid-range, even within one model.
Soundwise strat's can come loaded with very weak single coils pickups for that vintage 60s sound, 'hot' single coil pickups for that texas SRV sound and then humbuckers for that 'fat' metal/indie sound. You need to check out what that £400 beauty has in it and see if it matches your tastes.
Strat is a great shape but beyond that there's a world of differing instruments. Check out what makes like Tokai, Blade and Fret-King do with the strat. They may inspire you more than the usual Fender offerings...
'The sound of the city seems to disappear'