A stepfather who never raised the child and only became a stepfather after the child was grown, would not be a "real father" no.
You're absolutely right. There's a huge differnce between a stepparent who married the real parent when someone was a child and one when the child was an adult. And also a difference in age of child when the parent married.
My parents were divorced when I was 4. My Dad married my stepmother was I was 7 and my mom my stepfather when I was 8. So they were a huge part of my childhood.
But my husband's mom remarried when he was 25. While he loves and respects her second husband and the kids call him "Grandpa Bob" it's a lot different.