It's very close, and they do heat mold, so if the lower skate fits pretty well the top end skate should be able to fit pretty well as well.
For the most part this has been covered, but here goes:
Pricier skates will be much stiffer, which helps in protection. Padding isn't enough to stop a puck's energy, but a stiffer boot will help a lot. The most protective boots out there are the stiffest- the shot energy will be absorbed by the shell and won't even make it to the padding. I have taken 90 mph slapshots off the sides of my feet in Synergy 800s (Now SE10, one piece glass fiber boot) and had all pain go away in a minute or so. These are shots that would break a foot in most traditional leather skates.
The other big advantage is weight. Yes, it does help speed. A lot. Try putting ankle weights on, skating for a while, and taking them off. Your footspeed improves dramatically, which makes you faster and lets you remain fast longer into the game as it wears you down less.
The steel will also be better. Stiffer and stronger, so it holds an edge longer. The holder will also be better, transferring energy better. That along with a stiffer boot lets you put more energy into each stride, making you go faster, and supports you better, allowing you to make tighter turns. Cheaper skates also often come with holders with the steel molded in, so you can't replace it. If the steel breaks or runs out you're SOL.
You have better linings to help your foot stay comfortable, you have better tongues to help prevent lacebite and to add more padding to protect the least protected area on a skate.
Cheap skates are designed to be quick, cheap and easy to produce. Top end skates are designed to be the best thing they can make to skate and play hockey in, which usually means they're not cheap, quick or easy to make.