Renewing Passport Questions

Filling out form now and confused. Do i check us passport book only or do i need that and the passport card. Not sure whats point of passport card as i dont know what that is.
Also is 28 page book the one to choose or 52 page or it doesn’t really matter much? Are they same price? If so, why would anyone choose the 28 page as oppose to 52 page unless they don’t want a bulkier passport?

I have the 52-page passport, and IIRC it’s the same price as the 28-pager. I have no idea why anyone would choose just the 28-pager unless maybe they really don’t expect to travel that much.