The Hartmann mountain zebra has a dewlap which the Burchell’s does not. It seems lots of taxidermists - both in Africa and especially North America - tend to mount the Hartmann without the dewlap. Perhaps they treat all zebra as Burchell’s - which are more common by far.
The stripes on the Hartmann are also different - some have mentioned the lack of a shadow stripe on the Hartmaan, which is one difference, but there are others - the stripes on the rear of the Hartmann will almost invariably have a ‘fish bone” pattern, which you don’t see on the Burchell’s. The Hartmaan’s will also have stripes down to their hooves, while the Burchell’s tend not to have stripes which stop higher up on their legs. And as noted, the stripes on the face of the Hartmann tend to be lighter in colour than the rest of the body and lighter than you find on the Burchell’s - often quite tan in colour.
As for how they taste, I’ve tried both and find that they are the same, and I’m not a fan of either one. Yes, the fat on the Burchell’s is yellow, and there tends to be a fair bit of it, but that may be just an artifact of the diet of each - the life of a mountain zebra in Namibia tends to be harder than the life of a plains zebra in Africa, so they may tend towards less fat.
Lastly, the two (sub) species readily interbreed, and where game ranchers have not been careful, that happens, with unfortunate results for genetic purity. So you may find one type of zebra with some traits of the other.