LTR and EDACS can be scanned by most scanners made today, as long as they don't use Provoice on EDACS or are using Passport on LTR systems.
I monitor an LTR system daily in Sevier County, it runs in standard mode.
Passport and Provoice are variations of the standard modes, they just can't be tracked with todays scanners.
As far as their relationship to each other, there is none. They are two different trunking schemes owned by 2 different companies.