LESS or FEWER
We use LESS when we are referring to something that has no plural or cannot be counted. (for example, weather, time)
It refers to a smaller amount, not as much, or a decreased value of something.
“There was less snow than they expected.”
We use FEWER when we are referring to people or things in the plural.
Think of fewer as the comparative form of few, like a “few things,” or a “few people.”
“There were fewer chairs than guests.”
FURTHER or FARTHER
FARTHER is an adverb we use to refer to a physical distance. It is about an amount that can be measured and quantified.
“During the training session, Tim ran farther than Jake.”
FURTHER can be used as an adverb, verb or adjective. It usually indicates metaphorical distance or amount, and refers to things that cannot be specifically and quantifiably measured.
“The teacher asked Julia to further explain her answer on the test.”
“The house sustained further damage after the second storm.”
When in doubt, use further in a sentence when it can be replaced with “more” or “additional”.
Happy English learning!!