This version of Steel Gunner, designated 'Rev B,' suggests a revised edition of the original Japanese release. It is likely this version features adjustments or improvements to the original gameplay, graphics, or sound.  The date of this revision is unavailable in common resources, however, it would not have differed significantly from the original release date of its predecessor.  Without access to original developer documentation, the exact nature of these revisions is hard to ascertain.

Steel Gunner (Rev B)

Starblade (ST2, World)