Consumer Surplus

The difference between what consumers are willing to pay, and the actual market price

Here, there is a consumer that is willing to pay £4, while the market price is £1. This means they have a consumer surplus of £3 - The good is worth £3 more to them than what they paid for it. The area shown is all consumer surplus.

Producer Surplus

The difference between what a supplier would be willing to sell at, and the actual market price

Here, the supplier would be willing to sell at 20p for a given output level, so they have a surplus of 80p when selling at the actual price of £1. The area shown is all producer surplus

The consumer surplus + the producer surplus is known as welfare. If there is a loss in consumer surplus and producer surplus, this is a welfare loss.