Second character of the suffix is usually a revison which normally does not affect form, fit, or function.

If I remember correctly this is required to help keep track of things even when the part is the same but supply chain has changed.
A change of packager or tier 1 machine shop would require a suffix rev even though they're all supposed to be making
the part to the same specs, and you may not be able to see or measure any difference.

Anyway If I knew I needed an A*, I'd bolt on an AA through AZ without a whole lot of concern.