I'm not too familiar with LTN, but I think it's a bit simpler but also more opinionated than LTN.
Autotrains assumes that it's used in a very specific way, but makes that way very convenient. On the other hand, LTN (I think) lets you do more, but you'll have to "configure" more, and the result may not always be optimal.
An example of this is, that Trains that are controlled via Autotrains should always only have 1 Cargo/Fluid wagon.
I mainly made this mod because I had a very specific concept in mind how my trains should work, and it was a bit too cumbersome to set up with the mods out there. The idea was that trains basically work like drones: You have supplier chests, you have requester chests and you have the drone stations (depot). And the system figures out where to send send drones.
