Not all TV shows available to redownload on iTunes show up on Apple TV
They are all available, it's just a numbering and naming inconsistency between the devices. 

On the Apple TV, the "All TV Shows 12" is referring to the total number of distinct TV shows (example: Seinfeld, 30 Rock, The Office, etc). 

In the iTunes Store > Purchased section on your Mac, the "Total: 15 items" is referring to the total number of seasons of all the combined different TV shows. 

You have 3 seasons of "Peanuts Specials" (which iTunes treats as one distinct show) and 2 seasons of "Peanuts' Charlie Brown" (another distinct show). So the total number of distinct TV shows is 12.