The difference is why I dont do gas, it has a max run of 48h if you want to make the best profit so you cant take advantage of the price swings as you can with other stores. For example a full jeweler takes 1200-1500h to empty on R2 but if you can grab a good day its worth the 50m per k investment to stock it to the max

To give you some idea
Germany has the largest demand but its also got far more sellers
France has better prices on the whole but lower demand and high Q both of which are bad for your sales
Turkey is the weaker one of the bunch with low demand it can be seen as a dead end but its rapidly making up the ground as larger players move in to capitalize on the low supply to jack up prices so my guess would be that turkey could be a good choice later on down the line.
For now all my sales are in France due to the higher prices and almost equal supply on most products.
H