What's the difference between an AC Vent Cover and a Linear Slot

Aluminum Air Conditioning Linear Slot Vent Diffuser slot vent Linear Slot Vent Metal White 900mm comes with an adaptor box which means the vent can be connected to 150mm flexible ducting slot bonus deposit A 550mm long, 22mm wide Greenwood trickle vent Includes internal and external canopies which neatly cover routed slots to comply with building regulations

slot infini88 bonus 100 Expella's Linear Slot Grille is an internal ceiling diffuser designed for use with ducted inline ventilation systems which sits discreetly on the ceiling