Yes, even when chicks are small and fluffy, there are behavioral differences between the cocks and pullets.
The cockerels are usually fussy when you pick them up, where as a pullet will not fight as much (depends on the breed, but for the most part pullets don't fight as much as the cocks do).
If you watch your chicks a lot, you will notice that cocks are spunky. Pullets are more mellow; that doesn't mean pullets are completely tame or sweet, in fact, my Australorp hens are somewhat wild compared to my BO, for example. So again, it depends on the breed.
But guessing from the pic, yours looks like a gal.
wing sexing only works on certain breeds and at a day or two of age, not weeks. One reason I have never tried it. Looks like a pullet but wait a few more weeks to make sure
Im going to say a pullet. My Stumpy had more wattle and comb growth at that age, also they start to turn red around that age. My girls wattles didnt start turning red until closer to 8 weeks.