Wow I have to type all of this again
now I am getting irritated -.-
Cake: has icing, not as thick in consistency as fudge or brownies.
Brownies: on the thicker side but nothing compared to fudge, has no icing usually.
Sponge: is basically like a sponge that you would clean with but it's edible and more airier.
Fudge: Super thick, super chocolaty.