Digital cards would be those made using images downloaded to a PC. There are quite a few websites where digital card and scrap stuff is available for download - some free and some you have to pay for.
I recently downloaded some digital stamp images from a website in the UK called Pink Petticoat. They have digital kits available for purchase. I bought a couple of the kits and downloaded them to my PC. Then I can print off the sentiments/papers/images whenever I need to.
Hybrid cardmaking is when you use some digital elements mixed together with traditional techniques like stamping etc.
This is a card I made recently using a Pink Petticoat digital image and sentiment.
Big Bum Henrietta Hippo by FubsyRuth at Splitcoaststampers