Difference between IW501002 and IW500916 ?

Difference between IW501002 and IW500916 ? They both at called a IWC Big Pilot
Le Petit Prince?

Maybe im missing something, sorry if its obvious!

thanks in advance

Hello Andyollie, welcome to the forum. On the outside, these two watches
appear to be identical. The difference, however, is on the inside. Both have 7
day automatic movements, but the 5009 has the earlier single barrel (one long
mainspring) movement while the 5010 has the newer, redesigned twin barrel (two
shorter mainsprings) movement with a little more ceramic used in the
components. The movement redesign is intended to produce a more consistent
rate over the seven days as the mainsprings wind down as well as to reduce
wear with the additional use of ceramic. I personally have had fantastic
results with the earlier movements so I am not motivated to "upgrade" my big
pilots and I do service them at regular intervals so wear is not much of a
concern to me either. However, it is reassuring to know that IWC is comitted
to bringing the best possible product to market and will continue to make
improvments as technology changes.

Thank you very much for the detailed reply