Bondage refers to being restrained in some way, it could be being tied up with rope, being chained, being handcuffed, being gagged, being wrapped up or mummified with plastic wrap, cloth, tape, or any combinations of the above.
It can even mean mental bondage, such as being put in one place and told to stay there.
Discipline refers to punishment of some kind – normally spanking, caning, paddling, whipping, or other forms of chastisement. Discipline can also mean such things as standing in the corner or being sent to another room, or other forms of punishment which are not necessarily physical.