Different Units/specialty

In nursing school, I wasn't taught the difference between all the speciality. Can someone tell me the difference between step-down,  observation, intermediate vs regular med surgical, and recovery? Northwestern seems to have all these different unit name but barely any description of them! Also as a complete new grad with no hospital experience, is a "clinical resource unit" a good way to start off? I thought it was for more of experienced nurses who are there to help when in need.