What ingredient makes yellow cake different from white cake?

The key ingredient that makes yellow cake different from white cake is egg yolks.

Here's why:

* White cake uses only egg whites, which contribute to a lighter texture and color.

* Yellow cake includes both egg whites and egg yolks. The yolks contain a pigment called lutein that gives the cake its characteristic yellow hue.

While some recipes may call for additional ingredients like lemon zest or buttermilk to enhance the flavor and color of yellow cake, the primary difference lies in the inclusion of egg yolks.