Why would you choose one word over another, when the two might be synonyms?
The best explanation was provided by Isaac Asimov:
R. Daneel said, "I do not understand the distinction you are making,
Partner Elijah. Since 'murder' and 'homicide' are both used to
represent the violent ending of the life of a human being, the two
words must be interchangeable. Where, then, is the distinction?"
"Of the two words, one screamed out will more effectively chill the
blood of a human being than the other will, Daneel."
"Why is that?"
"Connotations and associations; the subtle effect, not of dictionary
meaning, but of years of usage; the nature of the sentences and
conditions and events in which one has experienced the use of one word
as compared with that of the other."
"There is nothing of this in my programming," said Daneel [...].
(from "The Robots of Dawn")