Some Commonly Confused Words

Advice/Advise 
Advice is a noun: Chester gave Posey good advice. 
Advise is a verb: Chester advised Posey to avoid the questionable chicken salad. 
Affect/Effect 
Affect is usually a verb: Chester’s humming affected Posey’s ability to concentrate.
Effect is usually a noun: Chester was sorry for the effect his humming had. 
Among/Amongst
Among is the preferred and most common variant of this word in American English.
Amongst is more common in British English. Neither version is wrong, but amongst may seem fussy to American readers.
Among/Between
Among expresses a collective or loose relationship of several items: Chester found a letter hidden among the papers on the desk. 
Between expresses the relationship of one thing to another thing or to many other things: Posey spent all day carrying messages between Chester and the other students. (binary relationships)
Assure/Ensure/Insure  
Assure means to tell someone that something will definitely happen or is definitely true: Posey assured Chester that no one would cheat at Bingo. 
Ensure means to guarantee or make sure of something: Posey took steps to ensure that no one cheated at Bingo. 
Insure means to take out an insurance policy: Posey was glad the Bingo hall was insured against damage caused by rowdy Bingo players. 
Breath/Breathe
Breath is a noun; it’s the air that goes in and out of your lungs: Chester held his breath while Posey skateboarded down the stairs. 
Breathe is a verb; it means to exhale or inhale: After Posey’s spectacular landing, Chester had to remind himself to breathe again. 
Complement/Compliment
A complement is something that completes something else. It’s often used to describe things that go well together: Chester’s lime green boots were a perfect complement to his jacket.
A compliment is a nice thing to say: Posey received many compliments on her purple shoes.
Disinterested/Uninterested
Disinterested means impartial: A panel of disinterested judges who had never met the contestants before judged the singing contest.
Uninterested means bored or not wanting to be involved with something: Posey was uninterested in attending Chester’s singing class.
Defence/Defense
Defense is standard in American English.
Defence is found mainly in British English. 
E.g./I.e. These two Latin abbreviations are often mixed up, but e.g. means “for example,” while i.e. means “that is.” 
Empathy/Sympathy
Empathy is the ability to understand another person’s perspective or feelings.
Sympathy is a feeling of sorrow for someone else’s suffering. A sympathizer is someone who agrees with a particular ideal or cause. 
Farther/Further
Farther refers to physical distance: Posey can run farther than Chester.
Further refers to metaphorical distance: Chester is further away from finishing his project than Posey is.
Gaff/Gaffe 
A gaff is a type of spear or hook with a long handle: Chester completed his sailor costume with a gaff borrowed from his uncle’s fishing boat. 
A gaffe is a faux pas or social misstep: Posey made a gaffe when she accidentally called Chester by the wrong name.
Gray/Grey
Gray is the standard American English spelling.
Grey is the standard British English spelling. 
Historic/Historical
Historic means famous, important, and influential: Chester visited the beach in Kitty Hawk where the Wright brothers made their historic first airplane flight.
Historical means related to history: Posey donned a historical bonnet for the renaissance fair. 
Imply/Infer
Imply means to hint at something without saying it directly: Chester implied that Posey was in trouble, but he wouldn’t tell her why. 
Infer means to deduce something that hasn’t been stated directly: Posey inferred that Chester was nervous about something from the way he kept looking over his shoulder. 
Loose/Lose
Loose is usually an adjective: Posey discovered that the cows were loose. 
Lose is always a verb. It means to misplace something or to be unvictorious in a game or contest: Chester was careful not to lose his ticket. 
Principal/Principle
Principal can be a noun or adjective. As a noun, it refers to the person in charge of a school or organization: Posey was called into the principal’s office. As an adjective, it means most important: The principal reason for this meeting is to brainstorm ideas for the theme of Chester’s birthday party. A principle (always a noun) is a firmly held belief or ideal: Posey doesn’t like surprise parties as a matter of principle.
Inquiry/Enquiry
Inquiry and enquiry both mean “a request for information.” Inquiry is the standard American English spelling. Enquiry is the British spelling. 
Stationary/Stationery
Stationary means unmoving: The revolving door remained stationary because Posey was pushing on it the wrong way.
Stationery refers to letter writing materials and especially to high quality paper: Chester printed his résumé on his best stationery.
Toward/Towards
Toward is standard in American English. Towards is standard in British English.

Who’s/Whose
Who’s is a contraction of “who is”: Who’s calling Chester at this hour?
Whose is a possessive pronoun that means “belonging to [someone]”: Chester, whose phone hadn’t stopped ringing all morning, barely ate anything for breakfast.

Via  Grammarly