2 replacement boxes

Xfinity contacted me, saying they need to replace my 2 cable boxes. But when they arrived, both boxes are identical and are very small. They are the same size as the secondary box we have now. 
Neither new box indicates it’s a primary, and our current primary box is about 10x larger than these new ones. 

Shouldn’t the primary box be larger? Or does this not matter anymore? If I disconnect the old primary box, will the new tiny box still have DVR capability?