Theer are 3 main types...
1. Plain Caulk. Cheap and does a ok job. Good for filling large gaps on the cheap. Does not hold up as well or as long. Easy water clean up. I use this kind mostly in garages, holes in buildings that need a base, etc...
2. Siliconized caulk. Cost more then regular caulk but usually last longer and has the same easy clean up as caulk. Looks similar to regular caulk as well. I use this where it might been seen a good deal and also has to take more wear and needs a longer life then 100% caulk will offer.
3. 100% Silicone. Cost the most, very few can take paint, harder to clean up, and has a glossy look that may stand out in a bad way. Offers the best sealing and long life. Much more resistant to mold and mildew. I like to use this where there will be water like sinks/baths etc...