Applications can be installed in /Applications or in the user’s ~/Applications, or even in both.
A simple function which, given just the creator code of an application, and without forcing the app to launch, will return the full path of the specific .app file that will be run.
-- e.g.
-- OFOC OmniFocus
-- OGfl OmniGraffle
-- DNtp DEVONthink Pro
-- Scrv Scrivener
-- etc
AppPath("OFOC")
on AppPath(strCreatorCode)
tell application "Finder" to tell (application file id strCreatorCode) to POSIX path of (its container as alias) & name
end AppPath