Please Adults only that may know!?

I have a 10 year old son and a 8 year old son.. My 10 year old is Skinny and tall.. and My 8 year old is Kinda chunky he weighs 83lbs. My Question is... My 8 year old I dont see his **I guess you may call them Nuts.. Its just not there..but his weewee is there of course... my 10 year old has his and hangs down.. I took him to his pediatric and he says its normal but I just dont know.. Please Im not trying to be funny or anything like that,, and no I dont look at my boys naked all the time. but it worries me and I just want to know why, how and if theres anything I should know.,. Please someone help thanks