Bottom bracket models Do I need to be concerned with the difference between a:

VP BC73 (https://www.halfords.com/cycling/bike-parts/gears-drivetrain-and-cables/vp-bc73-68-x-122.5-square-taper-cartridge-bottom-bracket-271445.html)

and

VP BC73A (https://www.tredz.co.uk/.VP-Components-VP-Sealed-Bottom-Bracket-Cartridge-Alloy-Cups_118565.htm?sku=452354)

apart from the difference in length of 2.5 mm (120 vs 122.5)?
No, they are basically identical.
neither of them will have fabulous life expectancy.