What's the difference between Brave Talk and Brave Talk Premium?

Are the differences between Brave Talk and Brave Talk Premium listed or discussed anywhere?

The only other similar question I see from a ‘search’ in Brave Talk Community wasn’t answered, except for a reply guessing that Premium offers calls to multiple parties (i.e., not just 1:1).

Also, one specific question:

Does Brave Talk match the features of Google Voice with respect to making/receiving phone calls?

Thanks.