Two customers with a Joint Checking account have equal ownership of the assets in the account. Each owner can transfer, deposit, and withdraw money. Upon the death of one of the Joint Checking account owners, the entire ownership is transferred to the surviving account owner.
On the other hand, a beneficiary does not have access, control, or ownership over the account while the account owner is alive. Upon the death of both of the Joint Checking account holders, the assets are transferred to the beneficiary.
Please note that after the death of one of the Joint Checking account owners, FDIC insurance (as provided by nbkc bank, Member FDIC) will decrease after a six month grace period to the amount covered by an individual Checking account.