To me, "app" was just short for "application", and it usually implied something more than a program. A program was more of an individual binary and its data fil

To me, "app" was just short for "application", and it usually implied something more than a program. A program was more of an individual binary and its data files. An application could be a suite of programs; basically, it was a superset of "program" that could include multiple binaries acting toward a common purpose. An "App" (mobile-style) is a new word. It implies (again, to me) a sandboxed program with a simplified, single-window, full-screen UI. The same 3 letters (app) have been used my entire life to refer to computer programs, but the connotation has shifted a lot.