Do centrifugal force and gravity differ in their effects on objects? If the type of object matters, consider the human body. If the situation matters, consider standing on the inside wall of an O'Neill cylinder compared to standing on the surface of Earth.
"Differ in their effects on objects" means: Would the object be able to tell the difference? That is, is there an instrument that could tell whether it is placed in an O'Neil cylinder or on the surface of a planet from the effects (acceleartion, I suppose) of centrifugal force and gravity alone?
 A: General Relativity is compliant with the Strong Equivalence Principle. According to this principle:

The outcome of any local experiment (gravitational or not) in a freely falling laboratory is independent of the velocity of the laboratory and its location in spacetime.

This implies that locally gravity is indistinguishable from acceleration. Thus the answer is that locally the effects of gravity and the centrifugal force are the same. Here "locally" means a region small enough where the force is uniform. For example, if the rotating cylinder is large and you are confined inside an elevator, you would have a very hard time telling gravity from acceleration. However, in a larger region, many different experiments and observations would easily reveal differences between the centrifugal force and gravity, as justly stated in the comments and the other answer. 
A: Yes. An instrument that can sensitively measure the force gradient (for example, the difference between the force at one spot and the force at a nearby spot, say a foot away) could tell the difference. This “tidal” force will be greater for the O’Neill cylinder.
A: What we normally think of as “gravity” on earth is actually a mix of gravitational and centrifugal force: plumb bobs don’t hang toward the center of the earth, but rather slightly toward the opposite pole.  They are both static body forces, so it’s not possible to directly tell them apart locally. 
But any rotating frame also has Coriolis force, which is detectable locally. 
