Is IBM's OS V7R2 the same as AIX?

It is one of the operating systems supported on IBM Power Systems alongside AIX and Linux as well as on IBM PureSystems alongside AIX, Linux and Windows. source

V7R1,2,3 is a sucessor of OS/400.

A fact on the name;

When IBM announced the new Power Systems line of servers on April 2, 2008, they renamed the operating system from i5/OS to IBM i[3] and changed the version identifier format from VxRxMx (Version, Release, Modification, e.g. V6R1M0) to the more standard format (e.g. 6.1).