Somewhat the same, but not exactly.
Our kids don't have the same bio-dad. When our middle dd started school, she came home and said her teacher told her, "She's not your sister, she's your half sister" in regards to our oldest daughter. We asked our middle dd what she said back, and (being herself), she apparently rolled her eyes at the teacher and said, "Duh! How can I have HALF a SISTER?!?!"
I love my girls!
If someone asked me, I'd just say "Yes, they're brothers." Because they are. Having different genes doesn't change that and strangers really don't need all of the back story.