I'm not sure that anyone really explained the difference between magic power & research levels ... so I'll give it a shot.
Mages are attuned to tap into sources of magical power. There are eight such sources: Fire, Water, Air, Earth, Nature, Death, Astral, and Blood. Higher levels of magical power represent the ability to channel more and more magic from a particular source. A Druid with N1 and a Great Mother (pretender) with N9 are both able to channel Nature magic. However, the Great Mother can channel a
lot more Nature magic than the Druid can.
On the other hand, research levels sort of represent magical techniques. There are a number of "schools" of magic: Conjuration, Evocation, Enchantment, Alteration, Construction, Thaumaturgy, and Blood. As one example, Conjuration represents your nation's knowledge of how to summon and (usually) control magical monsters, spirits, and other beings. Higher levels of Conjuration research will "unlock" rituals to summon more powerful critters. Simple Conjuration rituals summon silly Bog Beasts. (Sorry, Sombre, but it needed to be said.) Advanced Conjuration rituals summon the Kings and Queens of the Elements.
So how do these different "levels" combine? Your mages' levels of magical power determine what sort of magic they can control and how much of it they can use. Your magical research determines what they can
do with their magic. Fire mages can use a level 4 Conjuration ritual to conjure up Summer Lions, which are lion-shaped spirits of magical flame. Water mages can use another level 4 Conjuration ritual to conjure up Winter Wolves, which are wolf-shaped spirits of magical frost. If your nation has researched Conjuration 4, then your Fire mages will be able to conjure Summer Lions, and your Water mages will be able to summon Winter Wolves. That is, if you have
both Fire and Water mages in your employ....
The rituals for conjuring Summer Lions and Winter Wolves both require three levels of their magical "source": Fire or Water, respectively. A mage with fewer levels of magical power simply cannot channel enough magic to conjure these spirits. Even if you've done the research. He just doesn't have the power. But you can boost his power with magical items or empowerment, as others have already written.
All of this stuff is explained (better than I did) in the manual. I hope I've been able to clear up some of your confusion while you wait for the game to arrive. If not ... well ... just read your manual, and all will be clear.