Question about my body? been wondering for years?

ok, im 14 and i weigh around 175 lbs. i consider myself very overweight. at the same time, i run as fast as your average person without breaking a sweat, and my friend cant run 20 feet without panting and hes around my weight. also, i ran straight up a hill (almost sprinting) twice the length of a normal street without breaking a sweat and only panting slightly. my friend couldnt even manage to run and had to do the method where you move sideways while going slightly up to reduce effort (i dont know how many people know it) and he was panting very hard when he got to the top, and i was at the top while he was only halfway. if it makes more sense, he was carrying his laptop in a shoulder-sling bag, but even without it he cant manage it. i have that hump on my stomach area that shows im fat and i have some squishy body parts, but at the same time, im athletic and agile and flexible strong (i can lift and carry my uncle who is 30 and is also overweight) im about 5 foot 5 and im a guy. is some of this fat actually muscle? i know i have muscle but am i mistaking some of it for fat? i dont major in any sport im an all-rounder i usually swim, play basketball, or soccer, but im not in any league or tem, i just do it on my own time.