There are probably millions of synonym pairs in the english language, but as you set out to write a difficult passage or nail down the perfect topic sentence of an essay, you might find that some words simply can’t be switched with a supposedly equal synonym. It might even feel like your language skills have betrayed you as the words refuse to fall into order on the page.
I find I’m most confronted by this issue when I’m writing dialogues. The wording you use can impact whether your readers like are detest your characters. For example:
“I disagree, I think thoroughbreds are the best overall,” Said Sandy.
“You’re wrong. Thoroughbreds are always faster,” Said Katrina.
Would you rather be talking to Sandy or Katrina? I would certainly rather talk to Sandy. Both phrasings are used by people when debating in real life (just look at the presidential debates), but when you have the time to look at them on the page they’re full impact can be felt.
A significantly less belligerent example is shrub versus bush. Shrub sounds like carefully manicured landscaping whereas a bush can just as easily be found in a wild forest. So, I wouldn’t have an upperclass character refer to bushes when she could be referring to shrubs.
Furthermore, in an epic adventure you’ll find that a trip and a journey are far from the same thing. A trip involves point A and point B, but a journey indicates all of the events that occurred in-between.
The array of synonym options within the color spectrum is astounding. In physics you have three primary colors and three secondary, plus black and white. In prose “midnight gown” sounds more malevolent than “raven dress.”