The version number corresponds to the first major stability update issued for the Creative Cloud 2015 release cycle, aiming to resolve early bugs, memory leaks, and performance hitches present in the initial 16.0 launch. The Evolution of Photoshop CC 2015
However, the "Portable" label attached to this version refers to a of the software. A typical Portable Application (or "Portable App") is designed to run from a removable drive like a USB flash drive without being installed on the host computer's operating system. Adobe Photoshop CC 2015 16.0.1 Portable