No two synonyms are exactly the same: they may have subtly different meanings or be used in different contexts. For instance, the words blunt, candid, forthright, frank, and outspoken are all synonyms of each other because they all have roughly the same meaning, but there are subtle differences.
Do you know the difference between the following words? Follow the links to see how they are explained in the Oxford Thesaurus of English:
calm, serene, tranquil, placid, peaceful
decide, determine, resolve
hard-working, diligent, industrious
There are 120 'Choose the Right Word' panels in the Oxford Thesaurus of English devoted to explaining the differences in meaning between groups of close synonyms totalling well over 400. The distinctions are based on careful analysis of actual usage as recorded in the Oxford English Corpus. This analysis involved the most up-to-date computational techniques to sift large amounts of data, as well as traditional lexicographical analysis.