Right, Enlightenment is the ideal goal obtained by shedding desires and through mindfulness. The Buddha gained the knowledge of liberation through Enlightenment.
Enlightenment
So what exactly does it mean to achieve Enlightenment?
They both go hand and hand, Nirvana is a transcendent state where there is no suffering, nor desire, it is the ultimate goal. But in order to reach it you have to achieve Enlightenment first.
Nirvana
So what is Nirvana then because Enlightenment seems like the same thing?