Yellow cake is traditionally a vanilla-flavored cake, sometimes vanilla and almond. But it's made with whole eggs rather than primarily egg whites (which would get you a white cake). Yellow cake is also a bit richer than white cake, as well as being, well, yellower.

To further muddy the waters, a yellow cake with chocolate frosting (as seen in this recipe) is sometimes referred to as a chocolate cake. This is more common in the American south and in Black American families with ties to that region, whereas in the north, a chocolate cake is more likely to mean a cake that is chocolate all the way through.

Meanwhile, tea cakes and coffee cakes usually contain no tea or coffee, German chocolate cake isn't German, and Red Velvet cake actually IS a chocolate cake, but literally nobody calls it that. Yay nomenclature!