It will become obvious that you differ in some frustrating and subtle ways. Neither of you will understand the other very well, which will lead to feelings of mistrust and frustration. To your buddy, your grounded practicality will make you look more like a rigid stick-in-the-mud who refuses to take a chance in life; and their intuitive sense of the world and their reliance on their gut instincts will look to you like they really don't have a plan -- like they're too flaky to get things done in an orderly, efficient way.
In order to get along, you'll both have to try harder to get where your pal is coming from. You'll each have to set aside your skepticism about their way of looking at things, and instead, try to see things through their eyes. You just might learn that there's actually a lot about their viewpoint that makes sense -- and with hard work, you could eventually blend your viewpoints for an overall greater, more holistic perspective of the universe.