Velocity vs Capacity in Scrum

Scrum Team capacity and velocity calculated based on team's productivity and business value delivered to customer.
What is Team's velocity
Number of story points delivered/demo in a Sprint is called velocity. For example, if team planned 30 story point(Business value) worth of user stories in a sprint and able to deliver as planned then team's velocity is 30.
What is Team's capacity?
Total number of available hours for a sprint is called Team's Capacity. Available hours calculated based on resources planned holiday and company holiday if any.