cameyo is a complete virtual environment like thinstall before while p-apps need a full featured host. cameyo includes all necessary files, p-apps need host.
OK then perhaps I misunderstood. I think Cameyo in the past was more a bit like Sandboxie, which allowed you to run virtualized/portable apps.
FYI. PortableApps.com Platform 29.0: Freeware License Filtering and Improved App Compatibility Checks
FYI. PortableApps.com Platform 29.1: Improved Performance, Better Multilingual Support, Updated Locales