Methylated spirit is ethyl alcohol (the sort you drink) mixed with some chemicals to make you NOT want to drink it. The purpose is to enable alcohol to be bought at prices that do not include the massive tax in most countries for high alcohol beverages. It is used as a solvent for some adhesives, wood stains, cleaning etc. There are some people on the fringe who are "metho drinkers" with very bad effects on their health.

In this part of the world, the main "denaturants" are methyl alcohol, methyl isobutyl ketone, and denatonium benzoate. Methyl alcohol should act pretty much like ethyl alcohol, but I don't know anything about the others which are there in very small quantities, probably for their unappetizing odour.