Shared Memory
Shared Memory refers to memory component of a computer system in which the memory can accessed directly by any of the processors in the system.
Distributed Memory
Refers to the 'Network based memory' in which there isn't any common address space for several memory modules including the memory system of (networked) system. Normally, a processor or group of processors have a memory module associated with it, not dependent on the memory modules associated with other processors or group of processors.