Difference between IOperationBehavior and IContractBehavior?

I want to know what is difference between IOperationBehavior and IContractBehavior and what is special case when we can see difference between this two in development.

A WCF service can has multiple contracts.

• IServiceBehavior - applies to all contracts and can be applied thru the config file or the attribute
• IContractBehavior - applies only to one contract and can be applied only thru the attribute