One of my students is really fluent in English. I read her essay and had no suggestions or corrections. Her sentences are very complex and correction, and her grammar is perfect. I told her this. She complained that she needs help with vocabulary. (Note: students who really need ESL claim they don't and those who don't claim they do. Isn't that the case with everyone and everything?)
I looked over her paper and noticed that she used the word "different" many times, so I told her to use a thesaurus, on-line or book, and write synonyms. She said she didn't know how we use those. It's true. I'd never thought about it, but as a native speaker, I can read synonyms and get the tone, nuance or just usage.
Later, I stopped at Border's and saw a $15 thesaurus on clearance for $4. Most thesauruses (sp?) are about $5 or $6 anyway. This one, American Heritage, explains all the meanings. It claims for "different" that "difference" is the most general; "dissimilarity" is difference between things that are alike, such as twins; "divergence" suggests an increasing difference; "distinction" means a difference that is determinable only by close inspection; and "discrepancy" is a difference between things that should match. (American Heritage Thesaurus, page 191.) There you go! There are many differences among the synonyms for "different"!