CAC (Customer Acquisition Cost) is the total cost of acquiring a customer, while CPA (Cost Per Acquisition) is the average cost for each individual acquisition. CPA is calculated by dividing the overall CAC by the number of customers acquired during a given time period. While both metrics are valuable in their own right, CPA gives businesses more granular insight into how much they are spending to acquire individual customers and can help them make better decisions about budgeting and marketing strategies.