At first these two types of boots look very similar to one another, but still there is a slight difference between them, like the difference between an Oxford shoe and a Derby shoes. More about desert boots HERE.
The main differeces between desert boots and chukkas are:
(1) The sole – the desert boot has a sole made of crep, while the chukka has a sole made of leather or rubber.
(2) The side stitching – the side stitching on the desert boots will always be visible but on a pair of chukkas it won’t or you will see it just a little, depending on who made them.
(3) The laces – being a casual shoe, the desert boot’s laces will always be a bit thicker, similar to the laces of sneaker shoes. On the chukkas, the laces will always be round and a bit thinner than the ones on desert boots, just like the laces of a pair of business Oxford shoes.
(4) When to wear each of them – the desert boot, with it’s crep sole, sneaker-like laces and exposed stichings, is more of a casual shoe. The chukka on the other hand can be worn in business situations, such a going to the office, going to a meeting and so on, you can wear them with a suit no problem.