| Memcached | Redis |
|---|---|
| Memcached only does caching information. | It provides some more functionalities like replication and persistence along with caching information. |
| Memcached supports the functionality of LRU (Least Recently Used) eviction of values. | LRU is not supported by Redis. |
| In Memcached, when they overflow memory, the one you have not used recently (LRU- Least Recently Used) will get deleted. | In Redis, there is a time set for each function, Three keys are maintained, the one, which is closest to expiry, will get deleted. |
| CAS (Check and Set) is supported by Memcached. | CAS is not supported by Redis. |
| Array objects are needed to be serialized in order to get saved. We need to unserialize them for their retrieval. | Redis has got stronger data structures; it can handle strings, binary safe strings, list of binary safe strings, sorted lists, etc. |
| Memcached has at most 250 bytes length. | Redis has at most 2 GB key length. |
| It is Multi-threaded | It is single threaded. |