Rehab and RIT both assist fire/EMS operations. this would make the game more "advanced" and a little more technical if you wanted to use the equipment and training.
Rehab
Rehab units assist Fire & EMS on long term operations. Rehab is designated to providing food, drinks, and other basic life need like a restroom. These can be dedicated units that look like food trucks commonly called Rehab or Canteen units. a lot of areas also have units to assist in rehab with equipment, these are commonly Rescues, utilities, chiefs, platform, and larger ambulances.
RIT
RIT (Rapid Intervention Team) job is to go after firefighters in danger. RIT training should be required in groups of 4 depending on the call size, smaller structure fires (Commercial, Warehouse, drug lab) should require 4, medium (high-rise, hotel, hospital) should require 8, Large (CBNR, Chemical plant) should require 12. If you don't have RIT trained personnel you shouldn't be able to get these mission variants but theses variants will pay more