Twere not the same.
Indeed the words “Less” and “Fewer” are related and similar in meaning. Both are relative terms for dealing with numbers and quantities of items. But as it turns out, many among us tend to use them erroneously if not haphazard fashion i.e. as if they were interchangeable. This is much the same way that others confuse “Promise" with “Swear” and “Dream” with “Wish.”
“Less” refers to a indiscrete quantities as a mass of guano on the beach or a disappearing amount of water disappearing as from the Dead Sea (mimicking Lake Chad) in North Central Africa. It is correct to say that there is less water in the sea than a decade ago. One should, however, not say that “there is fewer water than a decade ago.” “Fewer,” on the other hand refers to a discrete number such as the rotting whales on the beach where biologists gleefully note that there are fewer such carcasses this year than there were a decade ago. But we would not say that there are “less” students in a school this semester versus last semester since it almost sounds as if we were measuring them by the ton and not counting them individually.
Similarly the popular media has broadcast thousands of examples of those who repeat “I promise” when they referring not to future performance but a representation of fact as “swearing” to some factual depiction.
And then, ever since The Rev. Martin Luther King spelled out his “I have a Dream” speech, we have tended to confuse a wish or longing for with the dreams that occur in REM sleep. One can articulate one's longings, goals and “ultimate prizes” as “Eyes on the Prize,” but few of us remember well our actual dreams.