Re: Difference between VNX Block Operating Environment and V
1) VNX Recovery Image need for back to fabric state of array (back-rev). This is disruptive procedure for data on array.
VNX Recovery Image also need for reimage one SP on array. This is NOT disruptive procedure for data and array's configuration. The array auto-perform to upgrade or downgrade to correct OE version on SP after reimage if you use not same version VNX Recovery Image.
VNX Block Operating Environment - this OS on array's controller (Storage Processor). Or do you mean bundle for the ordinary NDU (non disruptive upgrade) OS on array?
2) You need to use VNX Recovery Image for full reinstall or reimage array (back to fabric state).
3) Yes, if you use old version VNX Recovery Image for back-rev than you will need to perform NDU for uprgrade array to last OE version.