Michigan Craft Distilleries, And Microbreweries Expanding What is microbrewery? I asked this not too long ago, I felt like being a beer drinker I should know, lol. Well according to thompsonislandbrewing.com it is simple. A microbrewery makes less than 15,000 barrels of beer in a year, and that's not all. 75% or more of it must be served away from the site. The only difference between a craft brewery and a microbrewery is volume. A craft brewery does not have to be a microbrewery, but many microbreweries do make craft beer. also, a microbrewery does still have to have craft brewing rules to be a craft brewery.