Only one of them is methyl alcohol, the yellow one.
The red one (isoheet) is isopropanol (rubbing alcohol) and it burns sooty if it burns at all. Often it has so much water in it that it won't even light.

I don't buy it that way anyhow, gas line antifreeze is expensive.

It is a lot cheaper to buy methyl alcohol as fondue fuel or in the hardware store where it is sold with the paint thinners. It is used for thinning shellac.