Deposits are considered liabilities for a commercial bank rather than assets because they represent the bank's obligation to return the money to its customers upon demand or at maturity. In the context of banking operations, assets refer to the resources owned by the bank that generate income, such as loans issued and government securities. This distinction is crucial in understanding a bank's balance sheet and its role in the financial system, aligning with foundational concepts in economics and banking covered in NCERT and UPSC reference material.