While homeworld takes place in a single active environment at a time, SINS takes place in multiple environments at once.  Picture a giant battle around a detailed volcanic planet you are seiging.  A blazing starscape pierces the sky and subtle dustclouds blur your view.  Then zoom out to see the entire solar system map from deep space. Locate your newly colonized frontline ice planet and zoom back into build a capital ship factory and set your fresh fleet to hyperspace in to assist the ranging battle.  Then zoom really far out to follow up on your scout who just landed in an entirely different solar system - a calming blue starscape littered with rich terran planets and protective local militias.  There is no level loading or wait time between these scenes.  You could be building bases, fighting battles, and scouting the universe in a number of locations at once.  You could think of Homeworld as one of those battles. Throw in asteroid belts, wormholes, plasma storms, gas giants, and more and you can experience a very diverse environment.  One of the most notable differences would be the depth more typical of the 4X genre - research, diplomacy, NPC features, trade, and so on.  So, if you liked Homeworld 2, but wondered what was happening behind the scenes and across the galaxy, this is the game for you!