I found this page myself but it doesn’t really explain what the difference is between normal and enhanced. Will it increase the duration allow another stack to be applied or something else?

You kill an enemy, you get the buff (stacking up to 3). Buff is active until the duration goes to 0, in which case you lose all stacks at once. Enhanced reads like the buff duration is increased, meaning you have the firerate for longer and more time to get the next kill in order to keep the stacks up. DIM usually takes the descriptions from the game's API and the Bungies have never provided us with precise perk information. For the exact numbers, wait until the perk goes live. DIM will (after some time) list 'community insights' that carry actual numbers.