Bread machines bring home baked bread into the home, but they require specially processed yeast. There are differences between bread machine (also known as European, rapid rise or instant) yeast and active dry yeast.
Active dry yeast takes twice as long to rise as bread machine yeast. Traditional yeast needs two risings compared with only one with bread machine yeast. Bread machine yeast is more finely ground so it absorbs moisture faster. The sugars convert sooner to carbon dioxide and make the dough rise.
Active dry yeast creates a stronger signature yeast taste and aroma. Bread machine yeast has a more subtle smell and taste.
Some artisan bakers shun bread machine yeast because they prefer to stick to the traditional methods. Bread machine yeast was not widely available commercially before the mid-1980s.
Some forms of bread machine yeast have ascorbic acid as a preservative. Active dry yeast does not. Bread machine yeast has a softer outer shell. It does not need presoftening in warm water like active dry yeast does. The shell absorbs the moisture as it is mixed in the dough, which is why bread machine yeast can be added at the same time as the other ingredients.
Active dry yeast can be substituted for bread machine yeast in many recipes, but rising time and a second rising might be required. But for bread machines, as the name implies, the two yeasts are not interchangeable.