Redstone only goes towards one of the many portals its a “Many Input Portals to One Output Portal” for Redstone. While Sensors are “Pull from many Portals and get whats at Output Portal”
So a few examples:
Redstone is Push
Item Pipes are Push
Fluid Pipes are Push
Sensors are Pull
Molds are Pull
The Top Side of Hoppers is Pull
The Output of Hoppers is Push