Excuse and Pardon are easily confused words as both words can be used in the context of an apology. For example, when you wish to get past somebody standing in your way, you may say “Excuse me" and if you step on that person's toe, you say “Sorry! Pardon me".
However, basically you use pardon to convey that you did not understand what was being said or conveyed. So, for example, you say "I beg your pardon, will you be coming for the funtion tomorrow?".
The word Excuse can be used both as a verb and as a noun.
(i) Meanings of Excuse as a noun: reason; pretext; defense; justification; plea; apology.
(ii) Meanings of Excuse as a verb: forgive; let off; acquit; absolve; exonerate; exempt; relieve; discharge.
The word Pardon is equivalent to saying: what?; what did you say; could you repeat that?; come again?
Examples of Excuse:
1. The interviewer admonished the candidate for coming late and said not getting the bus was a lame excuse as he should have set out early keeping in mind traffic jams.
2. Being an ISC Editor is no excuse for being domineering and give aggressive responses; one must be polite to members at all times.
3. The boss excused Sarita from her work and allowed her to leave office early as her daughter was ill.
Examples of Pardon:
1. Shridhar did not quite understand the client's request and said "Pardon? Could you please state what is your request again?"
2. Ravi's mother told him to raise his hand in class if he did not understand what the teacher was stating and say "Pardon? Please could you explain that again?"
3. Now-a-days youngsters are very rude and forget the basic words of "Please", "Thank you" and "Pardon".
In the context of 'forgive', example of pardon: The thief begged the judge to pardon him and promised not to repeat the offence.