Avionics Help

I am so lost. I am trying to better understand avionics.
Specifically, communication electronics vs. navigation radio vs.
navigation products. More specifically, these are Rockwell Collins'
core franchises and I am trying to understand what firstly
Communication avionics for a commercial aircraft entails? Is this the
HF VHF stuff? What is the radio navigation then? What's the
difference.

What is Rockwell Collins really known for in terms of communication
products on aircraft? What do these products do?

Thanks so much!