Source:
MEMORY DEFINITIONS: http://www.computerhope.com/jargon/memory.htm
PHYSICAL MEMORY
RAM
Also referred to as the physical storage or the real storage, physical memory is a term used to describe the total amount of memory installed in the computer.
CACHE
Cache is a high-speed access area that can be either a reserved section of main memory or a storage device.
Memory cache is a portion on memory of high-speed static RAM (SRAM) and is effective because most programs access the same data or instructions over and over.
RAM CACHE
Another term used to describe L2 Cache. L2 is also commonly referred to as secondary cache or external cache. Most computers today come with L3 cache and/or L2 cache.
KERNEL MEMORY
The memory used by the operating system, which is protected and cannot be accessed by regular applications Also known as:
VIRTUAL MEMORY:Virtual memory is a method of using the computer hard disk drive to provide extra memory for the computer. Segments of memory are stored on the hard disk drive known as pages.
PAGE:page refers to a set amount of stored memory.