Apps is just the new buzz word to describe all the many type of programs that are available for your phone/tablet device, just like the PD scene on the Amiga, Public Domain name was used, but not all programs where public domain, many where Shareware or just Rave Demos.
I still think Amiga has one of the best app sites, AmiNet, and its path names and trees are better (
http://aminet.net/tree ) I wish some one would make a slightly better front end system like maybe apples done (where people can rate programs and screenshots of programs) for it and included full commercial programs you could buy and download AmiApps it could be called.