What is the difference between sales cloud and service cloud?

Service Cloud includes a service cloud console for cases, messages etc. Sales Cloud inlcudes functionality

The main difference is sales cloud is the sales module wherein you can find leads, accounts, opportunities, products, etc.. It is basically the module within salesforce meant to be used for sales or generating sales.

Service cloud on the other hand is the customer service module or service module within the salesforce. It is used to help out existing and future customers. You can also find the accounts, sales and solutions within the service cloud.