Visualize is more often used to creating a mental picture. Envision has a deeper meaning that includes imagining the situation becoming a reality. Someone might visualize themselves on a beach in order to relax. But envisioning might include figuring out how to take a real vacation. Where would they get the money? When do they have time in their schedule to take the trip? How will they get there? It still has an element of imagination. It's not usually actual planning, but it is mentally showing themselves that something is possible.

There's also 'envisage'.

I think this will help you to get a clearer answer :) http://www.pickthebrain.com/blog/visualization-vs-visioning-whats-the-difference/