The storage type MLC saves two bits per storage cell, the TLC type three bits per cell and the SLC type only one bit.
These names already adumbrate the difference. Three SSD storages are available: Single Level Cell (SLC), Multi Level Cell (MLC) and Triple Level Cell (TLC). If you deal with the expected life span of an SSD, you first have to have a look at the variable storage types of SSD drives.
Someone who aks this question in relevant internet forums, mostly gets a variety of most diverse opinions. Some years have passed and new chips and procedures have immensely improved the technology. However, the development of SSD technology hasn’t stagnated since then. In fact, the starting times of SSD drives weren’t easy: The first SSD storages suffered from firmware problems and decreases of power.