Can't figure out why, they both should do 90 damage as I have both damage perks. Incinerate does 100 damage and thunderbolt does 90 damage, does anyone know why?

I heard of a link between the illusion perk 'aspect of terror' and destruction, I have the aspect of terror perk but I don't have the 'intense flames' that gives fire the fear power when the enemy is at low health. Does anyone know anything about that?

Hm, are you counting the extra damage from enemy being set on fire?

I assumed it was because lightning damage does not only normal damage but also magical damage. Fire does only normal damage. So, it makes sense that lightning might do a bit less, because really you're doing so much more than what a fire spell does.

Quote from http://www.uesp.net/wiki/Skyrim:Destruction:
Fire spells, even without the "Intense Flames" perk have a fear effect on them, and so are affected by the "Aspect of Terror" perk from the Illusion tree. That perk gives an extra 10 points of damage to fire spells.

You don't have to have that perk for the +10 damage to apply.

Ah okay! Thanks