I wouldn't dream of saying this. (His head was covered with short stubble/bristles.)He had a short bristle on his head. Because he had used clippers to cut his hair very short.
Well, not currently.Bristle and stubble are usually interchangeable. However, I think stubble implies something that is not supposed to be there.
Stubble is the result of something being cut and growing back (including vegetation). Stubble is bristly in texture and can therefore be referred to as bristle. Some bristle, however, grows (or just is) bristly without being cut. The bristles on a boar are not stubble. The bristles of a paint or hair brush are not stubble.Whether a head or a face, I don't see a big difference between "bristle" and "stubble".