Homelander was created in a lab. Vought International was involved in his creation. They used some sort of genetic engineering to make him super - powerful. He was raised in a controlled environment where he was taught to be a hero but also had a lot of dark secrets hidden from him which later influenced his complex and often villainous personality.
One key element is that he was made in a lab by Vought. His upbringing in a controlled and somewhat false environment is also crucial. Plus, the fact that he was created as a product more than a person is an important part of his origin story.
Definitely. The comic version of Homelander is portrayed as having greater strength and capabilities. This is evident in his confrontations and the scale of his power displays throughout the comic series.