how exactly dose brewers yeast differ from bakers yeast?

Baking yeast is designed to produce more carbon dioxide than alcohol, in order to make dough rise. Brewer's yeast has gone through selective breeding to have higher alcohol yields and produce less gas (which minimizes foam in during fermentation).

But, using baking yeast to make wine or beer when nothing else is available will work if that's the only thing you have. It will produce a decent yield (I am assuming that if you are reduced to using baking yeast you're not too concerned about how the flavors are going to interplay). Lambic beers are made from wild yeasts which are more or less the same yeasts in sourdough bread. If you end up having to do this, keep in mind that there will be a lot more gas/foam bubbling out of the mash/juice you use (especially in the first 12 hours, and there will be a bit of a noticeable smell as it happens.

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There is a large difference in taste in most cases. IBakers yeast often will give off some very strange flavors that you don't want in your brew, but maybe you'll get lucky. If you are having trouble finding brewers yeast, I'd recommend you get on Amazon.com and order some. Shipping is usually about 3 days and you can get good quality yeast for about 2 dollars. Either way, happy brewing. Cheers

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