Have my shoulder muscles shrunk?

[Jackshund]

In the below comparison picture, the one on the left I took at the end of April, and the other one earlier today. Is it just down to the fact that the exact position of the two pictures taken aren't fully identical, or have my shoulder muscles, especially around my neck actually shrunk a bit?

Also, in the second picture, do you think there's any fat loss around the stomach area compared to the first picture? Again, the inexact positions are making it hard to tell.

I've been doing from April to now sit-ups, leg swings laying down, dumbell exercises leaning over my bed and laying down on the floor.

i.ibb.co/BGNJr1j/Picture-1.png (add the http before it).