Here’s a link to an interesting presentation about the different networks available for linking DMR repeaters together. While things in DMR are rapidly changing there are a few minor details that are now outdated, most of the document is very descriptive when comparing the networks. Have a look here. http://www.katyars.com/wp-content/uploads/2016/10/DMR-Networks-basics-KB5RAB-10-04-16-1.pdf