Bulging bottom

[yotamking]

Hi,
I recently got a new guinea pig: rocket. Compared to my other guinea pig pocket, it seems like rocket's genitals bulge out and are much more noticeable than pocket's. Rocket is acting normally and nothing else is wrong so I just want to know if this is something to worry about. I am attaching pictures of both my guinea pigs. Rocket is the White and grey one, the other is pocket. Both are males by the way.
Thanks.

Bulging bottom – Google Drive

 

[Siikibam]

Boars can have gonads of varying size - some smaller than others. Have a look at the guide below. How old are they both?
Boar Care: Bits, Bums & Baths