BROADCAST ~ Letting the network know you are sending bitcoin to someone.

When you click 'Send', your wallet signs the transaction with your private key and broadcasts it, letting all the other nodes know of your intention to transfer value so that they can validate the transaction.

MEMPOOL ~ A transaction waiting room

This is the 'waiting room' where validated transactions are sent to be picked up by a miner and added to a block.

BLOCK ~ A 'page' in the bitcoin ledger

The Bitcoin distributed ledger is made up of digital 'blocks'.

Each block contains verified bitcoin transactions that keep the global ledger accurate and current. They also contain the nonce, a time-stamp and a hash of the previous block, all of which contribute to the immutability of the bitcoin blockchain.

BLOCKCHAIN ~ The whole bitcoin ledger

The bitcoin blockchain, also known as the timechain, is the distributed ledger that contains every block, and every bitcoin transaction ever made since the Genesis block was mined by Satoshi in 2009.