What is the difference between an excuse and a reason? [closed]

Question

I've been told not to use excuses, as per a "set of ethics", that if I gave reason for being late for an appointment, for work, not being a mathematician, etc. But, I don't see a moral difference between giving a reason for doing/ not doing something, and making excuses. If the justification I have is not extraordinary, or is not fabricated, how is it seen as less moral than another answer?

UPDATE, Feb. 26th, 2017: Since the Moderators can't decide if this is a question that is "off-topic" or not, I've tried to word it a little different than before, as per the Help Center Guidelines ~ Philosophy.Stackexchange.Com.

According to this excerpt from the same, there are places on this site where the question fits:

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Answer 1

The philosopher J. L. Austin, in his 1957 paper "A Plea for Excuses", makes a distinction between justifications and excuses. Contrasting these notions, he writes:

In the one defence, briefly, we accept responsibility but deny that it was bad: in the other, we admit that it was bad but don't accept full, or even any, responsibility. (p. 2)

In one of his examples Austin considers killing:

this may be on the ground that the killing was done in battle (justification) or on the ground that it was only accidental if reckless (excuse).

In other words, providing reasons is a way to argue that your action was right, or justified. Presumably, you would do it again under the same circumstances. Offering excuses, on the other hand, is a way to argue for not being held responsible, e.g. due to factors beyond your control.

Answer 2

When an agent provides "reasons", she stands for, and takes responsibility for her action. It signals that the agent acted (wasn't passive), and acted under favorable circumstances for deliberate action: in clear mind, in possession of one's faculties, in possession of relevant and correct information, not under threat (duress), and without unexpected interruptions.

When an agent provides "excuses" for an action, it signals that she did the action, at least in part, because of some unfavorable circumstances, and would not have done it otherwise. She pleads for diminished responsibility, on the basis of some unfavorable circumstance for deliberate action, like: being retarded or disabled in some relevant way, being drunk, being drugged, being sick, being insane, acting under threat, facing an unexpected interruption (there was a train strike, the dog ate my homework), innocently possessing wrong information (he told me the time was nine o'clock) or being passive and not acting at all (I didn't push you, I just fell over).

In Western philosophy, these distinctions were first discussed by Aristotle, in book III of the Ethics, under the title of involuntary action.

Those things, then, are thought-involuntary, which take place under compulsion or owing to ignorance; and that is compulsory of which the moving principle is outside, being a principle in which nothing is contributed by the person who is acting or is feeling the passion, e.g. if he were to be carried somewhere by a wind, or by men who had him in their power.