The hospital and retail settings are very different from each other. In hospital, you don't have to type labels, deal with issurance companies, deal with patients, or any of that. In the hospital setting you will be exposed to a much wider variety of drugs, narcotics will be handled differently from the retail setting, you will have to deal with pyxis machines, annoying nurses trying to yell at you all day about missing meds, go on delivery runs, may or may not have to compound ointments, GI cocktails, enemas, irrigations, etc. You will also be taught how to make IV solutions, TPNs and depending on whether or not you have an Oncology unit, you might learn how to make chemos too. You will also learn how to operate the robot (we had one called an Omnicell), run lots of batches (cartfill, pyxis, narcs, IVs, oral syringes, etc) and reports throughout the day, stock and replenish drugs. You will deal with a lot of bulk drugs that are super heavy. Nurses are gonna screw up with narcs and create discrepancies that you may or may not (depending on your institution) have to fix. You will come across lots of very expensive drugs (some in the price range of over $10K so you'll have to be very careful when delivering), very powerful narcs, drugs with very short stabilities so they have to be delivered STAT and lots of drugs that will need to be refridgerated once they are sent to the different units. If your institution has a tubing system, you will learn which drugs can and cannot be tubed (never tube narcs and insulin) and you will sometimes see specimen that are meant to be sent to the lab and not pharmacy (and yes that also includes stool samples so handle with care). You might also be required to pre-pack drugs for unit dosing (if they are in bulk bottles). You will also be required to pick up credits from the different units and you must know how to prioritize (anything that has to do with regulating the heart will get priority over a reg med). You might also be in charge of dealing with crash cart trays, anesthesia boxes and so on. Be wary of codes and stay out of the way if you are not needed during a code.
You will also want to brush up on your drugs. You are not required to know everything before hand, so don't stress out too much. They'll teach you as you go along and you'll start to pick up on different things.
That's about it in a nutshell. Have fun. I enjoyed it (for the most part).