fume
English
Noun
A gas or vapour/vapor that smells strongly or is dangerous to inhale. Fumes are solid particles formed by condensation from the gaseous state, e.g. metal oxides from volatilized metals. They can flocculate and coalesce. Their particle size is between 0.1 and 1 micron. (A micron is one millionth of a metre)
smoke
English
Noun
The visible vapor/vapour, gases, and fine particles given off by burning or smoldering material.
all in all, it's as clear as mud. to my simple mind, smoke is from fires, fumes are from exhausts or chemical reactions but.....................