Butter cookies, shortbread cookies, and sugar cookies are different because of the different amounts of butter, sugar, and flour. Shortbread cookies have the highest ratio of butter to flour ratio which makes them the most crumbly in texture and most brittle. In comparison, butter cookies are sturdier and don't break apart as easily compared to shortbread cookies. This makes them perfect for packaging up as gifts! Sugar cookies have the lowest butter to flour ratio which also make them great for packing up as gifts. Sugar cookies are typically rolled flat and used with cookie cutter cut outs to make various shapes. They're great for decorating with icing for the holidays!