In Epiphan's recent video, George Herbert of Epiphan goes over the key differences between capture cards and hardware encoders. Both are hardware solutions but serve very different applications. Check out the video for a clear explanation of the differences between capture cards and hardware encoders.
"Epiphan Pearl hardware encoders simplify live video production with a host of advanced features along with professional-grade construction and components – all backed by rock-solid customer support. Epiphan also offers a complete suite of portable, USB-based capture cards, enabling users to capture signals from just about any video source."