There are three different types of isolation, and this subject is pretty cut and dry though it is important. I came to learn that when I had to miss a few days because of an outbreak.
Preemptive isolation means that they have not been diagnosed with anything contagious yet, but there is reasonable suspicion the patient might be. When a patient is in preemptive isolation, they have tests in the lab that have not come back yet to confirm that they have something contagious, or in other words "swabs". Above in the picture explains what precautions one must take before entering a room or a bedspace with this poster posted by it. It is the same as contact isolation.
Contact plus isolation is very typical at the hospital. Someone who is I'm contact plus could have anything from pneumonia to MRSA (MRSA was only explained briefly to me, but it's a virus you have contracted and will never be able to get rid of, and mostly occurs in the elderly). It's very common to see this poster in the hospital, and it is probably the most common. I think it is so common mostly because it doesn't take much to be put into isolation, a patient could have a cough and be put into isolation. Above in the picture is the standard procedure that needs to take place before entering a room with one of these posters. Another thing about contact plus is that, unlike preemptive isolation, the patient has to be put in his or her own room, or in another room with other contact plus type isolated patients.
Droplet isolation is a little more serious I suppose. Droplet is not quite as common, but in my time at the hospital, I saw it on a regular basis. The only reason I say droplet is a little more serious is because there are more precautions to be taken before entering the room. I'm also not completely sure, but I believe droplet isolated patients are not to share rooms, even with other patients with the same isolation type. It's called droplet because this means the patient can easily get you sick with some sort of body fluid. This might mean treach juice, blood, or even wet cough. There's all sorts of different levels, but you have to wear a face shield regardless. Above is a picture of what precautions one must take before entering a room with a poster by it.