/opt/local is for programs/libraries I created and smaller programs I downloaded source and compiled. /opt would be for canned items. For example, if for some

/opt/local is for programs/libraries I created and smaller programs I downloaded source and compiled. /opt would be for canned items. For example, if for some reason on Linux, I want to execute the latest Firefox or Thunderbird I would get the pre-built binaries and extract them in /opt. When I did that in the past, all items will be stored in /opt/firefox and /opt/thunderbird. Plus many proprietary objects like to be sitting in /opt in their own directories.