Flash Types.

MLC vs. eMLC vs. SLC vs. TLC

There are four types of NAND flash, differing in number of P/E cycles per lifetime, and defined by their construction:

• SLC -- Single Level Cell: the most expensive, longest lived (high P/E), and generally fastest. Bits are stored only as 2 voltage levels, or a "1" or "0." In SLC less data is stored per cell, so the per unit storage cost is higher.
• MLC -- Multi-Level Cell: is consumer grade and used in phones, cameras, and USB sticks. The stored charge in MLC may be interpreted as a variety of values, 0 to 3, or 4 possible states, and may store 2 bits. With shorter lifetimes, usually 10x less than SLC, the advantage of this memory is that the cost is 2- 4x less than SLC, but with lower write speeds. MLC typically uses some form of error correction code per block.
• eMLC -- Enterprise (grade) Multi-Level Cell: is MLC with longer life, usually because of an advanced controller operating the cell and error recovery techniques, construction density, or some combination of the two. 
• TLC -- Triple Level Cell: championed by Samsung, TLC has higher power and error correction requirements, and higher wear levels. TLC is targeted at environments with predominant read uses, and has not been commonly used. 

Regards

Gurudatta N.R