I’ve played both. Surviving Mars is definitely a more leisurely pace. I was able to beat the learning scenarios in OTC (some tool multiple tries) and did OK in one campaign game I played at a lower difficulty level. I didn’t find it unfair. It’s just hard to keep my eye on everything, especially what my competitor is building. I tend to focus a lot of just my area.
I don’t think it had the ability to pause and give orders when I played, but I think it did have that added afterwards - not sure though.
They really aren’t the same kind of game. It may be worth giving OTC another try and start with those learning scenarios. I think it was the 4th or 5th one that was very hard for me.