This is more or less similar to the Wargame series in gameplay. While not quite as Arcade as Wargame: Red Dragon this is still a casual game at heart and a lot more forgiving for mistakes.
Close Combat is a whole different beast that has a lot more to do with simulation and close quarter tactics than Steel Division ever will. The combat situations in it are short and brutal with 98% setup and planning with 2% action that decides the match. Steel Division is more of an ongoing conflict since you can keep reinforcing and have a lot more units and space to play with so losing that tank or street corner is not the end of the world, you can recover from it.
Steel Division also has a modern UI that doesn't try to fight you all the time when giving orders(sadly CC:GtC has one of the worse iterations of the series since it doesn't tell you when your units are under attack.)
And you
can see the whole map at once. This is probably the most important difference. It makes the game a lot easier to play and keep track of when you don't have to keep scanning all your positions every 20 seconds. You can just sit back with a cup of tea in your hand and wait to see where the first shots will come from.
That said, it will still require you to learn how to manage your attention. If you're coming from a TBS background you are used to spending ridiculous time and detail on everything. Forget that.
What's a lot more important is proper time/attention management. You don't need to know which of your soldiers are covering which window. You also don't need to watch them get to said windows. You've given an order, now let them do their job and execute it. You have more important things to do. Zoom out, breathe out, survey the battlefield, break that tunnel vision.
PS. Steel Division also has replays. So if you did tunnel vision and get back to the other flank only to see everything dead and burning, you can always check the replay to see what went wrong.
PPS. There's a game speed option in CC. Set it to slow if you feel things are happening too fast, it can help at the start.
TL

R:
Steel Division will have a far easier learning curve regarding tactics and units but there is still going to be one. In singleplayer it won't be too bad but multiplayer is going to be hard for anyone who has not played real-time games.