Tardy, late, behindhand, overdue can all designate persons or things that do not arrive or take place at the time set, the time due, or the expected and usual time.
Tardy implies a lack of promptness or punctuality or a coming or happening or doing after the proper or appointed moment; it need not imply slowness in movement but may suggest rather a being delayed in starting or beginning.
Late implies an opposition to early and usually connotes a failure to come or take place at the time due because of procrastination, slowness of movement or growth, or the interference of obstacles; it is applied especially to persons or to things that are governed by a schedule.
Behindhand usually applies either directly or indirectly to persons who are in arrears (as in the payment of debts or in the fulfillment of obligations) or who are slower than normal (as in mental progress, in the acceptance of fashions, or in taking action).
Overdue is applied to things that are affected by a person’s being, or less often to a person that is, markedly late or behindhand; thus, a person is behindhand in the payment of his rent, but the rent is overdue when such a situation occurs; a ship is overdue when it is seriously or conspicuously behind its scheduled time of arrival.
Overdue also may refer to something that might logically or suitably have appeared or occurred a long time before.