Not... exactly. Anyone can sneak, cast spells, uses bows, daggers, (any type of weapon), or any type of armor. Medium armor passives help sneaking abilities, regardless of class. Nightblades may have a couple abilities that benefit from stealth, and have (at last report) an invisibility spell.
Basically the class only dictates three (of 12) skill lines, and race dictates 1 (of 9) skill lines. Everything else is completely open, but you can't be a werewolf or vampire at the same time. You can also elect not to be a vampire or werewolf at all, and various fighter's guild abilities (mage and fighters guild have their own skill lines for those who join them) apparently hurt vamps and werewolves more.
The Tamriel Foundry has a general list of weapon and class trees up, but they are very much beta and subject to change. When things open up closer to release (particularly if an open beta happens) it will be relatively easy to get a clear picture of what the class abilities are like.