The best available info I could find is here:

https://embryo.asu.edu/pages/sex-determination-humans

https://guides.hostos.cuny.edu/bio140/13-44

https://academic.oup.com/edrv/article/41/3/bnaa003/5770947

TLDR: Every fertilized egg would develop into a female without chemical prompting. If a fertilized egg has a “Sex Determining Region Y,” gene it is likely to be male by creating the “SRY” protein. However the SRY proteins do not have all the information necessary to create a male. Some people with the SRY gene are not fully male.

A embryo with the SRY gene will likely create testes, which produce comparatively much greater androgens during puberty than embryos without testes. This results in:

>Marked changes occur in body composition during puberty that lead to boys becoming stronger and more anabolic compared with female counterparts. Androgens alone increase both whole body and muscle protein synthesis, though this is increased further in the presence of GH (236). Similarly, GH works synergistically with testosterone during puberty to reduce adiposity and increase lean muscle mass (236). Muscular strength accelerates rapidly after 13 or 14 years of age in response to rising testosterone and GH . . .

Testosterone also directly increases bone density and increases the effects of Insulin Like Growth Factor-1. All this results in greater muscle and bone growth than if the androgens were not present in the same quantities.

TLDR was TL so the Short, Short answer is:

Testes produce more androgens than Ovaries, especially during puberty, which results in significantly greater muscle and bone anabolic activity.