The Continuum transitions that are located in the host transition category are referred to as two input effects and automatically take a video feed from the outgoing clip and the incoming clip. The duration of the transition is always set using host controls and the Continuum transition will automatically retime itself to fit the transition length.
The Continuum transition filters that are located in the host filter category are single input effects and operate more like a standard filter. They’re quite useful when working in compositing hosts such as After Effects and include a percent done parameter which when manually keyframed will enable the user to create a transition in a compositing host, which doesn’t normally offer transitions.