The Tl;dr I give most people is that the Group Replication technology (innodb cluster) uses Paxos for group communication (with majority) and Galera uses Totem Single-ring Ordering (all nodes).
Interesting, I've been using galera clustering for a couple of years and the first months of setting up a new cluster, a new environment, have always been plagued by bugs and issues.
Eventually it stabilizes but I still have binary logs disabled because of an open issue over a year old.
I'm afraid that MySQL will have the same issues now that it's new.
The Tl;dr I give most people is that the Group Replication technology (innodb cluster) uses Paxos for group communication (with majority) and Galera uses Totem Single-ring Ordering (all nodes).