OptiPlex 990: Difference between "E" and "A" BIOS, Upgrade E11 to A19?

Hello,

we have got a DELL OptiPlex 990 here with BIOS version "E11". The current BIOS Version from DELL would be A19.

My two questions are:

- What is the difference between the BIOS of type "E" and "A"?

- Would it be OK to upgrade from E11 to A19? Remark: O990-A19.exe would allow to do so.

Thanks,

Wolfgang