Qr20

You are correct. If you remember your old huffy probably had a bolt on front wheel. To get the wheel off of the fork you needed a wrench. Well, today most mtb front hubs offer quick-releases (QR). For a lot of more aggressive applications (downhilling and free-riding usually) the quick release doesn't offer the stiffness needed, so the other option is a 20mm axle. Let's just say that a normal 20mm axle is a pain in the rear to take off. You will notice most downhill guys leave the front wheels on thier bikes when they transport them. To fix this Marzocchi came up with the QR20 system which was supposed to offer the stiffness of a 20mm axle with the ease of removal of the front tire from the fork as a standard QR. They later came out with QR20+ and QR20 Pro. They're just versions of the same basic principal. I think Rockshox's Tullio is the same thing. As for hub compatibility with the QR20, you would have to ask in the Downhill form. You may be able to use a normal 20mm axle hub or you could possibly have to have a special QR20 hub. I hope this helps a little.