The suffix -ance or -ence are the same and the difference in spelling is brought about by the vowels that precede them.
The words are derived from Latin forms ‘antia’ or ‘entia’, which generally mean ‘an act of’ or sometimes meaning ‘a thing that (does)’.
These noun endings are used to form words that stand for an action, especially one that cannot be seen by naked eyes, also called abstract. This is what makes words with -ance and -ence a bit challenging to understand because they are not used in visible things.
However, unlike prefixes, knowing the meaning of these suffixes will not help you know the meaning of the whole word where they appear but will shed some light on what should be the exact meaning of their root words.
You will therefore need to first know the meaning of the root words onto which the suffix is added.
For example, in a statement such as, ‘their performance was good’ we know that the word ‘performance’ which came from ‘perform’ and ‘ance’ mean the act of performing. This is the same as restating it as: ‘their act of performing was good’.
From what we have already seen, it would be a repetition to say that: their act of performance was good because -ance itself means act of. So it would be a repetition as saying that ‘their act of the act of performance was good’
Consider more other words like hindrance which also means the act of hindering, continuance which means the act of continuing etcetera.
For words that end in -ence, consider independence which also mean the act of being independent or not depending on others.
Other suffixes that mean ‘the act of’ are -sion, -tion and a few more others of Latin origin.
The act of educating will be called education (educate and -tion), while the act of revising will be called revision (revise and -sion).
The writer is a professional English Language instructor