What's the difference between Instant Video Ranker and Instant Video Ranker Content Engine?

Instant Video Ranker is the overall package. This contains the training, the step-by-step checklists etc.

The Content Engine is within this. It is the software element.

You use the Content Engine specifically to generate the content you need to copy into your video when uploading to YouTube.

Within the V.I.P. Edition, the software also generates keywords for you - use this to find low-competition, good-volume keywords - so you can rank for multiple keywords with one video.