What is the difference between ERC20 network and Ethereum network?

Could you please elaborate on the fundamental distinctions between the ERC20 network and the Ethereum network? As I understand, ERC20 is often referenced in the context of Ethereum, but I'm still unclear about the exact differences between them. Is ERC20 a separate network or simply a standard within the Ethereum ecosystem? If it's a standard, how does it interact with the Ethereum network? And how does this interaction impact the overall functionality and usage of cryptocurrencies based on the ERC20 standard? Your clarification on these points would greatly assist me in grasping the nuances of this complex yet fascinating field.