To add to the prev answer, the Show also has the Drop In feature that automatically accepts incoming video or voice calls. Many people set this up for their technically challenged family members or baby/pet/home monitoring. There's lots of limitation you can set of course (when, who, etc) for security purposes.
The screen size itself makes them suited for very different purposes. The smaller screen is best for times when a quick glance is useful (time, doorbell cam, etc) and the larger for when you'll really be looking at the screen (recipes, videocalls, etc).