Snzb-03 vs pu3

Can anyone help me undestand the difference between the snzb-03 and pir3-rf?
Why is one saying 433mhz? What is it about this frequency?
And if i get the 433mhz bridge, do i get better coverage or distance?

They’re different communication protocols.
The SNZB-03 communicates on the Zigbee protocol and the PIR3-RF communicates on 433mHz frequency.

If you have a Zigbee bridge you would use the SNZB-03 units and if you have an RF bridge you would use the PIR3-RF units. If you have neither then you can choose which protocol you like and buy the matching bridge and devices you need.