From Computer History Wiki
Memory is technology or hardware used to retain data to make it available for later use. The term is usually used to refer to things used as main memory, but it can refer to other uses of such technology, e.g. the caches often now found in disk device controllers.
The term does not usually cover things used for secondary storage (although some early, low performance - and therefore less expensive - computers used things normally now considered to be secondary storage, such as drums).