If I cast prestidigitation the first bullet point says:
You create an instantaneous, harmless sensory effect, such as a shower of sparks, a puff of wind, faint musical notes, or an odd odor.
So, a harmless sensory effect, would include these: Touch, smell, taste, sight and hearing. How far I can use visual sensory effects?
Can I conjure a small rain cloud above a creature's head?
Also what is the difference between this and illusions?
I need to know the limit, because the spell doesn't say the size of the effect, or its limits. Sight is a harmless sensory effect, so what the limit of the spell?