Although yams and sweet potatoes are both angiosperms (flowering plants), they are not related botanically. Yams are a monocot (a plant having one embryonic seed leaf) and from the Dioscoreaceae or Yam family. Sweet Potatoes, often called ‘yams’, are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea or morning glory family.
A muffin is any quickbread (mixed by muffin mixing method & does NOT contain yeast) that is in the shape of a cupcake. A cupcake is any cake batter mixed with the straight method or creaming method made into the shape of a cup. Cupcakes (traditionally) have frosting on top, while muffins have no frosting, but muffins can have a glaze on top. Many people think that the difference is either frosting or no frosting, or that it's "in a paper liner" or not, but that is a common mistake. Either one can be made with or without a paper liner; it's just the baker's preference. A quickbread (or muffin) CANNOT be baked like a sheet cake or round layered cake because it won't bake properly. The same goes for a cupcake batter - a cake batter (or cupcake) cannot be baked in a loaf or bundt pan because it will not bake properly. But, since both can be baked into a smaller shape, people often think they're the same.
...and I yam someone who has a muffin top when I wear jeans, with a backside that looks like a sweet potato-that turns the cupcakes off...
