Date/Time is stored as a Double datatype. The date component is the number of days since 30/12/1899 while the time is the fraction of a day after the decimal.
Time format has a date component of zero (30/12/1899) which Access automatically supresses.
If you have a single DateTime field in the table each control (that is what they are called in Access, not fields) on the form can be bound to the same field but display a different format.