blizzard had already announced they will have individual ladders like warcraft 3.

if you have not played warcraft 3 RTS ladders before, its like....Wings of liberty will have its own ladder, Heart of the swarm will have its own too. and they will have different units too. which means, wif wings of liberty, you cannot play heart of the swarm's multiplayer. and thus having different ladder too.

its like 2 entirely different games.

hope u can understand because i think i didnt explain well >.<