Asset custody refers to the business that qualified commercial banks, as custodians, sign entrusted asset custody contracts with clients, safely keep entrusted investment assets, and perform relevant duties of custodians. There are many types, including securities investment fund custody, entrusted assets custody, social security fund custody, enterprise annuity custody, trust assets custody, rural social security fund custody, basic old-age insurance personal account fund custody, supplementary medical insurance fund custody, income and expenditure account custody, QFII (qualified foreign institutional investors) custody, valuables custody and so on.

"Third-party depository" is a business provided by commercial banks, which is often used in securities, futures, real estate and other trading activities. Taking the third-party depository in securities trading as an example, it means that according to the requirements of laws and regulations, the depository bank is entrusted to take charge of the deposit and withdrawal of customers' funds and the delivery of funds, and the securities trading operation remains unchanged. Securities trading settlement funds of clients of securities companies shall be deposited by banks. This business follows the principle of "securities firms manage securities and banks manage funds", and strictly separates investors' securities accounts from securities margin accounts.

This is to find their own explanations in Baidu Encyclopedia, and the feeling is still different.