Tomato Shibby - features in Max vs. VPN

I'm looking at these two files for a E2000:
http://tomato.groov.pl/download/K26/build5x-123-EN/tomato-E2000-NVRAM60K-1.28.RT-MIPSR2-123-Max.bin
http://tomato.groov.pl/download/K26...2000-NVRAM60K-1.28.RT-MIPSR2-123-IPv6-VPN.bin

How can I tell what features are in each?

Also, what's in extras-mips{1,2}.tar.gz and can these be added to any firmware or only specific router models?