In brewing, the yeast is given sugars to convert into alcohol and carbon dioxide in the absence of oxygen.

In baking, the yeast is given some starch which is breaks down into sugars using its enzymes and in the dough, since there is a lack of oxygen, they convert those sugars into alcohol and carbon dioxide.

Those processes are both anaerobic respiration but in the first case, the alcohol produced is used and the carbon dioxide not, whilst in the second case, the carbon dioxide is used (to make bread soft) and the alcohol is not used (it's evaporated in the oven).