What is the key factor that differentiates muffins from cakes?

Muffins are characterized by a denser texture compared to cakes, which makes this the key differentiating factor. The denser structure of muffins comes from the way they are mixed and baked. Unlike cakes, which usually require a light and airy texture achieved through creaming butter and sugar together and incorporating air, muffins have a more straightforward mixing method. The ingredients are typically combined until just blended, resulting in a thicker batter. This leads to a crumb that is more compact, creating the unique denser mouthfeel that sets muffins apart from cakes.

The other options do not accurately capture the defining characteristics of muffins relative to cakes. For example, muffins can vary in sweetness depending on the recipe, and they are not universally sweeter than cakes. Additionally, muffins do not require longer mixing times; they often benefit from shorter mixing to prevent overmixing and ensure the desired texture. Lastly, while muffins can be enjoyed warm, they are not always served this way, and it isn’t a defining characteristic as many cakes can also be served warm or at room temperature.