There are a few key differences between house league basketball and Rep league. The biggest one is the level of competition. In Rep leagues the goal is to win, and kids are expected to be at a higher skill level and commit more time for training and traveling. In house leagues, the kids are proportionately competitive to their age, as fun and learning is the higher focus.
Participation is another main difference. Since the goal in Rep leagues is to win, kids are picked to play based on skill level. The benefit to house leagues is that all kids get a fair chance to play.