Braxton hicks or just the baby?

It's been happening for weeks now where my belly feels like it tightens up, bulges out and feels very hard when I put my hand on it. I've been thinking it's just when the baby is pushing his bum out but reading what braxton hicks feel like it sounds like them. I really don't know this is my first baby. I know they're normal so I'm not worried but just curious to know if it is actually them. Does it sound like braxton hicks? If it is then what is it that pushes out causing my belly to rise up in a ball shape?