"What are the biggest differences between the Marble Brown-LR and Moccachino-LR"
That is an excellent color question. The swatches of the two colors make them seem like they are very similar, but honestly, Marble Brown-LR is the darker of the two.
The light ash brown, light honey brown, and soft gold blonde blend of the Mochaccino-LR color is much lighter than the darker blend of the light brown and dark blonde in Marble Brown.
Below are the links for Heather's videos wearing both colors:
Tessa by Noriko, Color: Marble Brown-LR
Mochaccino LR (on Kai by Rene of Paris)