“app" might imply Applicable, Personal, and Portable, rather than only the abbreviation of APPlication. For the following reasons, 
    Applicable, yeah, app could not be system utilities, only provided for purpose of application.
    Personal, app could not be copied onto other's computer or even another partition of this same HDD, tricks are exceptions.
    Portable, no matter Windows 8 or Windows RT, no matter IA-32, x86-64 or ARM might potentially share the same app without worries.
    OK, that is only my guess.