As my kids got older, we upgraded to Lego system track and I was initially very disappointed in it. The math for Lego track is quite different and there is something very satisfying about the Duplo system.
The key difference is that switches in Duplo are equivalent to two oppositely curved tracks overlaid on each other. This means you can pop a switch in anywhere that there is a curve piece. In the Lego system track, it is a straight piece with a curve out and back in slightly. If you place two switches together you can connect two parallel tracks, but it has the disadvantage of being harder to place (you end up needing substantial straight sections to use switches)
There are a number of third party companies that are filling the missing links (literally) for Lego track geometry. It can be worth investing in - I’ve always been annoyed that the Lego switches are clearly for sidings and yards and not for loops.
As my kids got older, we upgraded to Lego system track and I was initially very disappointed in it. The math for Lego track is quite different and there is something very satisfying about the Duplo system.
The key difference is that switches in Duplo are equivalent to two oppositely curved tracks overlaid on each other. This means you can pop a switch in anywhere that there is a curve piece. In the Lego system track, it is a straight piece with a curve out and back in slightly. If you place two switches together you can connect two parallel tracks, but it has the disadvantage of being harder to place (you end up needing substantial straight sections to use switches)