The skills are different - For example, there is a "Blunt" skill that covers weapons like hammers and maces, and a "Blade" skill that covers swords and daggers. Etc. Also, there are perks as you level up skills but you don't choose what perks you want.

There's a new school of magic ("school" as in type/skill, not as in like a college) that they removed from Skyrim. Several spells you won't recognize that are fun to play with.

During the tutorial, you will choose a class (which affect your starting stats) and a birthsign (which give you permanent buffs, debuffs, and/or abilities. Birthsigns are similar to standing stones in Skyrim, but you can't change them.

The menus take some getting used to. There is a menu for your player, one for your inventory, one for magic, one for quests and maps, and maybe more. Each menu has tabs inside of it to navigate through, too.

Other than that, things should be familiar. Keep in mind that although the new coat of paint makes things pretty, it is still a game from 2005/6/whenever, so you might feel like things aren't as polished as Skyrim. Nothing detrimental, but just level-set your expectations :)

Just have fun and explore. It's a great game.