A supply line in Factorio is a conveyor belt
Or maybe a train line. I haven't played that far in Factorio to unlock trains. In Satisfactory, you can use conveyor belts, trucks, trains or drones. You should definitely give one of those a try if you like this sort of thing. They aren't colony sims, though. You do all the work yourself. which is actually better because you don't have to rely on the AI to follow your instructions. For instance, with a truck line, you actually get in the truck (after crafting it) and drive it to record the route you want it to take when you automate it. After that it just runs by itself until you tell it to stop. And, yes, I've been run over by a truck running its route haha
Factorio might feel a little more like a colony sim because the graphics are very basic and it's top-down, but you still have to move a little man around. Satisfactory is first person and generally more realistic in mechanics and automation than Factorio. The main thing you will be crafting in Factorio are different colored potions, as opposed to Satisfactory where you craft things like rotors, screws, etc. No idea why Factorio did that.
One of the biggest differences between them is that in Factorio you are constantly under attack by alien species who can destroy your base. There are enemies in Satsifactory, but you just find them walking around. They can't hurt your base.
Also in Satisfactory, resource nodes, like iron, don't run out. In factorio you are constantly having to rebuild because nodes go dry.
I'm definitely more of a Satisfactory person. I like to build things once and not have to worry about them being destroyed or running out of stuff. Plus the recipes are more realistic and intuitive.
Generally speaking, the people who like Factorio more are are the ones who really want to be fighting a lot rather than automating. Base defense is a huge part of it.