Both CRM (Customer Relationship Management) and Marketing Automation refer to software.
CRM works by collecting and managing customer interactions, with a focus on sales.
Marketing Automation focuses on optimising and refining marketing activities that garner new prospects and leads.
Marketing Automation software also serves as a CRM. While both terms refer to software and activities, they are not interchangeable. Think of CRM as a way to increase sales, and Marketing Automation as a way to ensure you are marketing your product or service to the right people.