The short answer
PVC is stiffer and cheaper per square metre. PP is tougher and recovers from impact. Use PVC where the panel is supported and mostly washed; use PP where an animal will lean on it, bite it and hit it.
How each material behaves
Rigid PVC is an extruded hollow board with internal ribs. It is dimensionally stable, easy to cut and holds a straight line well. Under a sharp impact it can crack, and a cracked chamber takes in water.
Polypropylene is injection-moulded solid. It flexes under a knock and comes back. It is more expensive per square metre and less stiff for the same thickness, which is why PP panels are 50 mm thick where a PVC board is 30 or 35.
Where PVC is the right choice
Room dividers, corridor walls, farrowing and weaner pen divisions, bench and service surfaces — anywhere the panel is supported at its edges and the loading is people and water rather than animals.
The PVC range also gives you the profile system: H-connectors, U-channel, corner posts and L-trim, which is what turns boards into a wall that can be dismantled and reconfigured.
Where PP is worth the extra
Grow-finish pen fronts, gate faces, any panel in a feeding rush, and every position that sees direct daylight. For daylight, specify black — carbon black is the most effective UV stabiliser available in a moulded panel, and a non-UV panel in a curtain-sided house will chalk and go brittle.
PP is also the material to choose where hygiene inspection is strict: a solid moulding has no internal chamber that can take in water through a crack.
Mixing them in one room
This is normal and sensible. Both mount in the same post and bracket system, so a room can have PP on the pen fronts and PVC on the divisions behind them. The schedule is counted from the layout, so the difference costs nothing in complexity.
What does not change between them
Neither corrodes. Neither needs painting. Both take a high-pressure gun and standard farm disinfectants, and both are produced in white and grey, with PP additionally in green, black and blue.
