metasploit package includes the open-source framework and the commercial Rapid7 part. While metasploit-framework package only includes the open-source part.
Compare the size of corresponding directories, the size is same, they don't differ:
Code:
# metasploit-framework package
rookt@kali:/# cd /usr/share/metasploit-framework
rookt@kali:/usr/share/metasploit-framework# du -s
151044
# metasploit package, that incorporates the framework
rookt@kali:/# cd /opt/metasploit/apps/pro/msf3
rookt@kali:/opt/metasploit/apps/pro/msf3# du -s
151044
The only thing that comes to my mind is that some external tools may be dependant on the metasploit framework location at /usr/share/metasploit-framework.