They're essentially the same piece of kit but the Parrot runs on a couple of AAx batteries (which actually means it has a longer battery life) and the Parakeet has a built-in, rechargeable lithium-ion battery that you plug in to charge.
The Parrot does have a few extra features - it allows you to adjust the microphone and audio volume levels independently and has a mute function. Both transmitters can be used with our Eikon Microphone!