eDRAM

These explanations are somewhat technical, but maybe I can explain since this is in my line of work. Some of it may not apply to Apple products though.

eDRAM is embedded DRAM. It just means DRAM on the same silicon die as some other electronics such as a CPU or perhaps in the same package in what's called a "multi-chip module". I don't believe Apple uses any yet. It's kind of specialized as most semiconductor processes for DRAM aren't well suited for "random logic" like a CPU.

DRAM is "dynamic random access memory". That's typically what's used for the main memory in any computer or other device. Technically it means each bit consists of one transistor and one capacitor so it requires less area per bit than other memory types. The term "dynamic" doesn't mean it's faster, but that the state of each bit inherently decays and has to be read and "refreshed" periodically to maintain the state of the memory.

SRAM is "static random access memory". It's generally faster than DRAM but requires more transistors and takes up more area. It's pretty much never used for main memory, but may be used as cache.

Cache is kind of hard to explain. It can mean different things. The basic idea is to use a faster memory/storage that might be accessed repeatedly, or to write faster. The most basic is SRAM on the same piece of silicon as a CPU to store memory contents that may be used over and over again. That would be "level 1 cache". There might also be level 2 cache or even level 3 cache on another chip or on the board. Hard drive and SSD controllers use what they call cache, which is usually DRAM. They're used as a buffer to store data either being written or being read. With read data it may improve performance if the same part of the data is being accesses\d repeatedly. With writes it just accepts it quickly and can then complete writing it to the disk or NVM (usually flash) later.

This isn't for a class project is it?