What is the difference between Salesforce sales cloud and marketing cloud?

Salesforce Marketing Cloud is an email marketing automation which connects interactions from any channel or device, and combines customer data and behaviors to create real-time relevant communications.

Salesforce Sales Cloud puts everything you need at your fingertips—available anywhere. From Social accounts and contacts to Mobile, Chatter, and Analytics, collaboration across your global organization and getting deals done faster is not only possible, it's easy.