Switching from Honeywell T8570 to Peco T180

I have a new Peco T180 to replace the Honeywell T8570 in my condo. I was studying the wiring and I was able to match 7 out of 8 wires.

The one wire from Peco T180 is Brown (Outside Air) which I can't figure out where it matches the Honeywell.
As for the Honeywell, the Violet (Fan Common) is the wire that I can't match up with the Peco.

Hope you don't mind me asking but would the Violet in Honeywell match up with the Peco Brown wire?

Or, do I just use 7 out of 8 wire of the Peco and leave the existing Violet wire from the wall capped and also not use the Peco Brown wire?

Thank you for your assistance.
Oscar

P.S. What is Outside Air and Fan Common?