Moral, ethical, virtuous, righteous, noble are comparable when they mean conforming to a standard of what is right and good.
Moral is the most comprehensive term of the group; in all of its pertinent senses it implies a relationship to character or conduct viewed as good or bad or as right or wrong. Sometimes moral implies relationship to or concern with character or conduct as distinguished especially from intellectual or physical nature.
Moral also applies to such things as literary works, works of art, and philosophies, or to writers, artists, and philosophers concerned with the determination or teaching of principles of right conduct or good living.
The term also applies to men or communities, to acts, or to conduct in the sense of conforming to the accepted standard of what is right and good, often specifically in sexual conduct, or of conforming to the customs or conventions of a people regarded as binding laws.
Ethical primarily implies a relationship to ethics, the branch of philosophy which deals with moral principles, or more specifically with the principles governing ideal human character and with the ideal ends of human action.
Although ethical is often used interchangeably with moral, it characteristically gives a slightly different impression owing to certain subtle connotations; thus, ethical principles may, according to the context, convey a strong suggestion of principles derived from a certain school of ethics, or of a formulated code behind them, or of an idealistic quality; an action is often described as ethical rather than moral when it accords with what the writer or speaker believes to be a higher or finer standard of morality than the one generally accepted, or when it is in keeping with the code of ethics governing a profession (especially law and medicine); the phrase "an ethical person" often differs from the phrase "a moral person," in suggesting an assent to ethical principles or an attention to the niceties of ethics or to the ideal ends suggested by a system or code of ethics.
Virtuous implies the possession or manifestation of moral excellence in character; in its most general sense it implies rectitude, justice, integrity, and all other virtues, but in more restrictive use and especially as applied to women, it often means little more than chasteness or perfect fidelity in marriage.
Righteous differs from virtuous chiefly in its stronger implication of freedom from guilt or blame; as applied to persons, it often implies justification, especially worthiness of salvation in the theological sense.
As applied to acts, conduct, and even displays of passion, it usually implies justifiability and often consciousness of rectitude <righteous indignation> But righteous is the one of these words that is freely used in a worsened sense to imply an invalid and sanctimonious assumption of the appearance of rectitude.
Noble (see also GRAND ) applies to persons, their acts, utterances, careers, or lives, and implies the possession and exhibition of a conspicuously high character. Often the word carries no other clear implications and seems little more than a term of high praise implying moral or ethical eminence.
At other times the term suggests not only moral eminence but the absence of all taint of any such petty or dubious thing as self-seeking, self-interest, or concern for the world's standards; it then often suggests independence, or magnanimity, or high courage, or some other outstanding moral excellence.