Lore wasn't a mere jerk - he was a maniac with an inferiority complex. Laas was just rude.
Pretty much. Lore worked with the Crystalline Entity to take down his home, and tried to take down the Enterprise too. While posing as Data. Killed Dr. Soong, also while posing as Data. Then later manipulated Data into torturing Geordi while ruling over a bunch of freed Borg with plans of galactic domination or something.
Laas was just a rude guy who only killed one person in self-defense.