Before I present my list, I should warn you that these come from my experiences working with mostly Japanese speakers, so the mistakes you see here may or may not be a problem for people whose native language is closer to English.
Why Was Z Removed From The Alphabet (And Then Put Back)?
Poor lonely Z finishes up the alphabet at number 26. But, that’s not the only insult this lonely letter suffers!Z’s history includes a time when it was so infrequently used that it was removed from the alphabet altogether.
When thinking about words which are synonyms of each other, it may be helpful to think not in terms of "What's the difference in meaning?" but "Are there differences in how these are used?" In other words, what other words and phrases does each word pair with?