Besides the obvious sun and wind factors, theree certainly is the court speed. This can be controlled during contruction by the amount of acrylic top is put on. The amount of sand in it and the swirling of the surface change how the ball "bites" into the court. A smoother surface will enable a ball to skid, or pick up speed once it hits and stay lower. A slower court, the ball bites into the surface and sits up for the hitter.
Of course an outdoor court can be done the same, one way or the other, but the indoor courts tend to be smoother and thus play faster. The surface is also not replaced anywhere near as often as an outdoor court.
Besides all of that, there are other things that are real factors. The height of the ceiling and the ceiling material, color of the ceiling and the type of reflective lighting. This is the second biggest issue for an outdoor player when playing indoors - lighting. But it may actually be the biggest factor since it is key to adjusting to the court speed.
At CS the indoor arena there have offwhite, almost a gray ceiling tile that absorbs light, so the court area is darker, making it difficult to see the ball like you can outdoors. So when an outdoor team has to play indoors, this is also a big factor that has to be overcome quickly.
Personally I do not like playing indoors because of the lighting and the courts are harder and hurt my knees. This is a result of less topping on the court and not being young anymore. The best surface is clay.