MLC
Considered the consumer-grade flavor of flash, Multi-Level Cell architectures can store two bits per cell. Although it may seem like packing more than one bit into a memory cell is a good use of space, it comes at the cost of a lower useful life and decreased reliability. MLC SSDs make it possible to economically add flash storage to PCs and laptops, relatively speaking.
eMLC
Enterprise Multi-Level Cell is a hardier version of MLC NAND flash that somewhat bridges the performance and endurance gap between SLC and MLC. eMLC drives costs more than MLC drives, but much less than SLC their counterparts. Although it still stores two bits per cell, an eMLC drive's controller manages data placement, wear leveling and other storage operations in a way that extends an eMLC SSD's useful life.