It's not a stupid question, and no, they are not the same. In hotels you'll have your own private room that other guests (besides those with you, of course) do not have access to-- meaning it's theoretically more secure. That being said, hostels aren't always a hotbed of thieving activity. They certainly can be, so it pays to take some precautions like putting your bag in a locker with a padlock, and always keeping your important stuff-- money, passport, tickets, camera, etc.-- on your person in one way or another.
For 4 to 5 people it *might* be cheaper to book into a smaller hotel or pension rather than pay individually for hostel beds. But it will probably depend on where you are. The search engine on the TravelPunk main page
lists both hostels *and* hotels, it will give you a good place to start off.