Answer:
While in general terms Columbus and Isabella shared a common goal, their true motivations were a bit different.
Step-by-step explanation:
Columbus' original goal was to find a shorter route to Asia by sailing west. The reason why this was important was because otherwise ships had to sail all around Africa to get to Asia. The Europeans' interest in Asia had to do with commercial trade. What Columbus was interested in was being a pioneer; being the first one to discover this new route.
Isabella was certainly interested in what Columbus proposed, but her interests were mainly focused on the economical aspect. She simply wanted Spain to control this new trade route. This way Spain could have easier access to Asia and all of the products and resources that the Europeans wanted, and that way they could later sell those products and make a profit.