Each time Chainlink creates a new price feed, for example AAVE – USD it creates four unique contacts (This is likely to become five, but more of that later).
Each of these contracts belongs to a distinct contract type.
The 4 contract types are
AggregarorFacades are essentially helper contracts that enable the original aggregator feeds to implement the same interface as the new (FluxAggregator) contract.
The AccessControlledAggregator is commonly known as the Flux Aggregator. A deep dive into Flux Aggregators can be found here.
The fifth contract category that is likely to be added to the stack, is the OCR (Off-Chain Reporting) contract.
This contract type is also known as the Offchain Aggregator. An introduction to OCR can be found here
ChainLinkGod.eth @ChainLinkGod discusses the stack in a recent tweet
The Chainlink blog " Circuit Breakers and Client Diversity Within the Chainlink Network" can be found here