Diablo isn't an mmorpg, its just an action-rpg with co-op and trading. MMO's are generally persistent worlds, i.e. life goes on after you log off. EVE takes the persistent world concept to its logical conclusion, as many things in the game take hours, days, even weeks.

When you die in WoW you are inconvenienced slightly for like 5-15 minutes. And if you have a warlock in your party you can resurrect so its only a problem when the whole party gets wiped out. WoW is a pretty fun game but its not pvp oriented at all and the quests are repetitive and not particularly rewarding. Crafting and trading are really dumbed down. It's just a grind to get experience and loot.

EVE is pvp-dominated but there are vast swaths of space that have security; computer-controlled ships that insta-pwn you for aggressing someone who you aren't formally at war with and who hasn't agreed to a duel. Secure space isn't 100% safe though, very often people use cheap ships to "suicide gank" people who travel through secure space with precious cargo. But long story short, if you aren't interested in pvp there's still a lot to do. The grindy aspects of WoW don't really exist in EVE. In EVE your character advances passively over time. Grinding tons of hours of time will only allow you to accumulate money or items, but it will still take real time to advance your character's skills.