It is all about airflow: where it does and does not go. A lot of the cabinets currently in use are BSC’s (Biological Safety Cabinets). Yes, they are still called Laminar Flow Hoods (LFH’s), but that is like calling a pizza oven a microwave.
At UMass Amherst, we are systematically converting from the LFH’s to BSC’s, as the old equipment is replaced. Why are we doing this? The BSC is a better, more versatile piece of lab protection equipment. The LFH protects only the product in the hood such as sterile media, while the BSC protects the user and the product in the cabinet from bacterial contamination.
Go to Biological Safety Manual