not to rebuke this or anything but those are technically the follow through on those shots. what i am trying to say is, you can take photos of almost anyone and chances are most player with sound techniques will all look the same.
This. Also they are both on the same court so it looks super-similar.
Fed's head-turn is crazy. I know people are taught to watch the ball go into the racket, but he turns his neck pretty much 180 degrees. Dmitrov does not do it as dramatically.