Welcome to grammar lesson two in the Nerdhappiness series on appropriate use of terms.
For our previous look at the nuances of "i.e." and "e.g.", click here. This clarification may be a bit simpler than that, however it may be more important given the more frequent use of comparisons in speech and writing. (For example, people would say "less" and "fewer" significantly more frequently than they might choose to say "i.e." or "e.g." Most folks that I know would choose "like " or "such as" instead.)
Over time, these two terms are being blurred together more and more. I find that kind of annoying.
My colloquial understanding has always been that "less" is to be used when you're talking about unknown amounts of a substance, while "fewer" is appropriate when you know the exact quantities of whatever you're describing.
For example, "Susan has three fewer apples than Nate," and "there is less water in my bottle than in yours" are both correct.
Imagine those statements with "less" and "fewer" switched. How awkward is that?
Upon some research, I have found that "fewer" refers to number, while "less" refers to scale. Which is than what I had previously thought.
M-W.com provides the following examples:
"Their troubles are fewer than ours," meaning "Their troubles are not so numerous as ours."
"Their troubles are less than ours," meaning " Their troubles are not so great as ours."
I like the revised definition better. It still accounts for my previous notion, but it's more elegant. So, remember. Fewer => Number, and Less=> Scale.