Confused about place in TdZ vs Zwift Power

I know there are a lot of questions and answers about ZP rankings and such so apologies if I’ve missed this explanation.

I did the C stage in the Tour de Zwift yesterday. During the ride my position showed as around 150 out of around 450 or so and I think I finished at around 129 or so - can’t remember exactly (I know it’s not a race).

Today when I looked at ZP and filtered for the C route, it showed me in 80th position out of around 140.

I don’t understand the discrepancy. It isn’t just this particular ride, I’ve noticed this in previous stages and races also so I figured I’d ask. I don’t really care that much about my actual position but I’m interested in understanding more about what I’m seeing and reconciling differences.

Zwift Power is a separate service to which not everyone who uses Zwift signs up. So it will always show fewer riders in an event and moves your relative position upwards.

Ah, makes sense now. Thanks!