【Command】 , 【order】 , 【injunction】 , 【bidding】 ,  【behest】 , 【mandate】 , 【dictate】 mean a direction, that must or should be obeyed, to do or not do something.

【Command】  imputes to the person who issues the directions either unquestioned authority or complete control of a situation. The term usually connotes either peremptoriness or imperativeness.

【Order】 is not always clearly distinguishable from 【command】 ; it is, however, the preferred word for directions to subordinates that are instructions as well as commands; in such use it commonly implies explicitness in detail.

【Injunction】 carries a weaker implication of imperativeness than the preceding words except in legal use, where it is applied to a court 【order】 commanding a person to do or more often to refrain from doing something on the penalty of being adjudged guilty of contempt of court.

In general use the word stresses admonition without losing the implication of expected or demanded obedience.

【Bidding】 , chiefly literary, usually implies the status of master or parent in the person who issues the orders and therefore stresses expected obedience or the fact of being obeyed.

【Behest】 is also distinctly literary and equivalent to 【bidding】 in its implications.

【Mandate】 (see also 【MANDATE】 2) carries the strongest implication of imperativeness of all of these words, for it denotes a 【command】 or 【order】 issued by a very high, often the highest, authority. It has or has had specific applications, such as an 【order】 from a superior court or official to an inferior one or from a Roman emperor to the commander of his military forces.

It is often applied to something inexorably demanded (as by the exigencies of the situation) rather than actually or verbally commanded.

【Dictate】 basically denotes a 【command】 given orally. More often it applies to a 【command】 or authoritative judgment uttered by an inner voice (as of the conscience) or formulated in a principle or law.