The X-Rite i1Studio Spectrophotometer is portable, easy-to-use, all-in-one integrated color-management solution that provides display and RGB/CMYK printer profiling with a streamlined interface. Key features include:
Monitor calibration and profiling
Color profile management
No! It is against the law to rent a software license. However, you can find a link to download the free software here.
As best we can tell, the hardware itself is largely the same. The main difference is the newer X-Rite i1Studio software offers a different user interface and additional profiling modes for B&W printer and mobile device profiling.