An Assistant Manager supports the manager in daily operations and team coordination, while a Business Development Manager focuses on identifying opportunities, building client relationships, and driving business growth. The Assistant Manager assists in managing existing processes, while the Business Development Manager has a strategic role in expanding the organization's market presence and revenue generation.
If you are interested to learn more about this then I would suggest you to check out this video on how Lalit Joshi achieved a career transition from an Assistant Manager to a Business Development Manager just after completing Intellipaat’s Salesforce Certification Course