What is the difference between AirPrint, Bonjour and Rendezvous?
First Rendezvous = Bonjour = unicast DNS
I forget why the name changed from Rendezvous, something about what Apple (used to) call it and what everyone else called it. It’s a server less DNS solution so devices can query locally, self-assemble, and discover services without needing a pre-configured DNS server / database.

https://en.wikipedia.org/wiki/Multicast_DNS
http://www.multicastdns.org/

AirPrint is a standard Wireless Printing protocol so that diverse printers all look like a standard printer, eliminating the need for specific drivers for specific printers. In the same way that LPR (Line Printer Protocol)is a printing protocol as well as IPP (Internet Printing Protocol). Here’s some Apple support / marketing information:

https://support.apple.com/en-us/HT201311 (AirPrint specifics)
https://support.apple.com/guide/deployment-reference-ios/intro-to-bonjour-apd0401947ff/web (Bonjour DNS)

Per wikipedia: &quot;AirPrint is based on mDNS (Bonjour, more specifically) and Internet Printing Protocol (IPP).&quot;(https://en.wikipedia.org/wiki/List_of_printing_protocols#Wireless_protocols)