The PoE switch vs PoE Injector? what is the difference?

Both PoE switch and PoE injector can supply the power to a PoE compatible PoE devices including IP cameras, access points, VoIP phones. There is a switching function integrated into the PoE switch. You need multiple PoE ports to work with several IP devices. The PoE switch is a handy tool. The PoE switch can connect multiple IP devices and provide data exchange. The PoE injector can convert non-PoE ports from the router or switch to PoE capable. You only need to attach the PoE injector to one of these ports, you can PoE output from non-PoE equipment. There is no need to replace the existed equipment before you can upgrade some of the ports to supply PoE.