Compared with protists, metazoans represent a huge change in the organization of animals: they are multicellular. While this is obvious, it is worth pausing to reflect on what multicellularity accomplishes for both an adult organism, as well as the embryo. Multicelluarity allows for several things (you could probably add to this list, but these are some of the most salient features of multicelluarity):

Food for thought: Can you think of a region of the fertilized amphibian egg that if inherited by certain cells during cleavage, might impart different properties on the cells that inherit them?