Hi Nirvana98109, I understand Winston's logic - and he's correct, but I do feel there's a probem with iCloud Photo Stream after updating my Apple TV to 6.0.
I used Aperture to remove 795 photos from my Photo Stream and did a fresh reload of the same 795 photos back into Photo Stream from a back-up. Both my iPhone and iPad show 795 photos, but Apple TV stops at 338. If I sign-out of iCloud Photos and sign back in again the pictures are out of order and the total picture count drops (i.e., to 337).
On previous versions of my Apple TV's operating system, I would perform the same procedure above and all devices, and Apple TV, would recognize the exact number of photos.
In the meantime, I stay signed out of iCloud Photos on the Apple TV and simply use "home sharing" until a fix is known.