As with anything, the more precise and in depth you try to catalog things, the more complex it becomes. This is especially true in numismatics. Krause is probably one of the biggest culprits.
One the one hand, continuing to further specify and itemize the varied coin varieties that exist for each type of coin, as well as listing their opinion of the retail prices for each, helps anyone in numismatics to be able to valuate items within their collection with ease. Yet, on the other hand, when one is not quite familiar with a specific series, such itemization of varieties can lead to confusion, just as with this coin.
As far back as 1971, the Krause catalog of that year simply states six coins to the Vichy French State series 50c: 1942, 1943, 1943B, 1944, 1944B, and 1944C. Plain and simple! The 1971 catalog lists this particular coin all as simply V94. Easy enough! Now you know that any of those dated 50c will have the exact same design!
Now, come the 21st century!

Interest in numismatics has literally exploded with the advent of the internet and feeBay. More people than ever before are buying and selling coins (under some slightly false notion that there is fast, mad money to be made). Knowledge and information is needed to keep up with this new trend. Thus, we now have KM914.1, 914.2, 914.3, and 914.4 to cover what in the days of old was simply V94.
Fun stuff

Pretty much, as a pointer with the Krause catalog, you can pretty much expect that coins listed under a particular picture will look like what's listed. Specifically to your question, the current KM914.1 is for the normal, or thick flan, no mint mark issues while KM 914.4 is particularly for the thin flans of the same type. You will notice that the thin flans in a higher grade command a slightly higher price for 1942 but a lower price for 1943 compared to the thick flan strikes. It is because of these difference in price that Krause was led to create 914.4 on not simply keep all no mint mark coins under the same number.
Enjoy your journey through numismatics as you continue to learn more and more about your coins and their history