Mosaic in Namespaces allows you to have a unique naming in the system and also to create assets. Someone may name it a "color coin" and others a token. Still, this system was called Mosaics since it will eventually turn into something more than a simple colored coin. In essence, this is an element of a mosaic panel, a tile that will have various kinds of properties, the list of which will expand as NEM develops. The overall NEM pattern is formed from such tiles.
Mosaics have a strict hierarchical structure.
Mosaic properties can be customized.
Batch processing of mosaics is possible, for example sending multiple mosaics in a single transaction.