Two compounds can be compared if they have any physical features to distinguish between them. For example, between a solid and a liquid, a solid will have a higher bp than a liquid due to the very high intermoleular forces of attraction that is present in solids. 

Comparatuvely, if you are given two liquids which are almost similar in properties, like methanol and ethanol, it would be impossible to predict which will boil faster than the other. However, very roughly, some predictions can be made. The longer the hydrocarbo chain, the greater will be the viscosity anf higher the bp. So, in that case, methanol (with one methyl group) should have a low bp than ethanol (with two methyl groups).