--prefix to /usr/local or /opt?

For building apps from source like git or rails I've seen recommendations to install in both /opt or /usr/local.

From what I've read so for, the designated use for both is about the same and it amounts to merely a style issue.

Is there any practical difference? Best practices?

From serverfault Paul Alexander

• The FHS says:

  A package to be installed in /opt must locate its static files in a separate /opt/ or /opt/ directory tree, where is a name that describes the software package and is the provider's LANANA registered name.

  while /usr/local hold the usual /bin/, /lib, /etc, ... hierarchy

  From Florian Diesch

• I use /usr/local for stuff I put into the system, and I let third-party installers take /opt.

  From Ignacio Vazquez-Abrams

• Personally, I like to install everything I build from source in /opt, and edit my $PATH accordingly. It instils a sense of (semi-) cleanliness, and it's easier to traverse the folder structure, perform updates etc. It just comes down to personal preference; one is not necessarily better than the other (just like you said, a style issue).

  From thepurplepixel