thin flan or thick flan? [resuelto]

What is the difference between a thin flan and a thick flan? (East Africa 10c KM26)

Thanks,

The coins from 1937 till 1941 are struck on a thick planchet and weigh 11 g.
The coins from 1942 and 1943 are struck on a thin planchet and weigh 9.4 g.

My digital caliper isn't working properly anymore, I think I have to change the battery. If I find one I let you know the difference in thickness.

https://en.numista.com/catalogue/pieces2862.html

Thanks for the anwer.
BMPJ