Hi /sci/ TL;DR how does competitive inhibition work?

So back in biochem, I learned that if some one gets methanol poisoning giving them more ethanol could save their lives by stoping the methanol from being metabolised. The reason for this being that ethanol will competitively inhibitate the same enzymes that methanol get brokendown by.
My question is why? Why does ethanol get brokendown first? Is it more accessible due to being a bigger molecule or does it have to do with chemistry? Ty in advice