As someone completely uninterested in Esports, i need help understanding the "houses"

Could someone please explain to me what these houses are? This reminds me slightly of the battle for the Freljord in seasons yonder, but is very clearly Esports themed and as such probably not significant in any way.

Even so, i do not like making permanent decisions without knowing what i'm getting into. What are these houses, and why should i pick one over the other? I am personally leaning towards The United because i love the aesthetic of the emblem and i love green, but i want to know if these choices actually affect anything else than visuals first.