Bound, bond, indentured, articled are comparable when they mean obliged to serve a master or in a clearly defined capacity for a certain number of years by the terms of a contract or mutual agreement.
Bound not only stresses the obligation, but it also often connotes a condition of or approaching servitude. It frequently implies the status of an apprentice, one obliged to serve a master for an agreed term in return for being taught a trade, a craft, an art, or a profession.
It may, however, imply the status of an unskilled laborer (as a domestic servant) who agrees to serve (as in a distant colony) in return for transportation, keep, and, sometimes, a wage.
When the condition of servitude is emphasized and service without a wage is implied, bond (placed before the noun) is often used in place of bound.
Indentured implies apprenticeship and emphasizes the fact that the agreement is in writing, has been executed in duplicate, and has legal validity. Usually it carries the implication of fairness and equity to both parties to the agreement.
Sometimes, especially in reference to an apprentice in a law office, articled is preferred to indentured, though there seems to be no clear distinction between the two.