I have always had one testicle is hard and the other is soft . no lumps, a lack of sponginess and the tubes going from it, are not so well developed

Doctor can evaluate: Some people have one normal and one less developed testicle. A primary care doctor can check and examine the testicles, and of course the prostate if a guy is old enough for that. Testicles are easily scanned by ultrasound to see what's inside, to rule out tumors, etc... A urologist can follow-up if the ultrasound says anything other than normal. The ultrasound can measure the testes sizes.

Recommend: medical evaluation to better understand the anatomy that you are describing.