To me difference is similar to a .280 vs a 7Rem Mag. If they're both shooting... let's say a 154 gr bullet, the 7 Mag will go a bit faster, and therefore shoot a bit flatter. Will the .280 be out of it's league to take the same shot? of course not. Just have to make a bit more of an adjustment in the shot.
To me, the 7Rem Mag and the .270 WSM are very, very similar [but obviously the .284 bullets can get heavier than the .277 bullets] and the .270 is very very similar to the .280. So the question is not "which will make a better hunting cartridge?" because the .270 and the .270 WSM will both be great hunting cartridges. The question you need to ask yourself is "Do I want a magnum?" the magnum will give a couple hundred more fps velocity with added recoil and quite a bit more cost [if reloading then the added cost isn't as much, but is still more than a standard cartridge].
So to answer the original question: is there a difference between the two? Yes. The difference is added recoil, more cost, to gain a couple hundred fps. Will the magnum make you a better hunter? unlikely. Will it make you a better shot? Also unlikely. In fact the added recoil could help you develop a flinch, so it may make you a worse shot. In a real world hunting situation the .270 is every bit as capable as the .270 WSM. But if you want a magnum, then go ahead.
I have a couple magnums. I like them, but I'm under no delusions that they're oh-so much better than my standard cartridges. But sometimes, you just want a magnum. Nothing wrong with that.