My testicles feel different on the inside

Male, Age23, H&W= 5'9&147lb, smoker, no medications, previous medical problems, recent complaint, location testicles

I was feeling up my testies when i noticed after 23 years of having them that they're not alike on the inside.

One of them (left) is big and has a brain like structure while the other(right) is a small rubber ball that floats around my scrotum. From the outside they're not that different in size.

I tried to ask on other subs but they're locked for me so I'm asking here before i went to a doctor because it's freaking me. Thank you in advance