The difference between Decline and Reject

When used as nouns, decline means downward movement, fall, whereas reject means something that is rejected.

When used as verbs, decline means to move downwards, to fall, to drop, whereas reject means to refuse to accept.

check bellow for the other definitions of Decline and Reject

Decline as a verb (intransitive):

To move downwards, to fall, to drop.

Examples:

"The dollar has declined rapidly since 2001."
Decline as a verb (intransitive):

To become weaker or worse.

Examples:

"My health declined in winter."
Decline as a verb (transitive):

To bend downward; to bring down; to depress; to cause to bend, or fall.
Decline as a verb (transitive):

To cause to decrease or diminish.
Decline as a verb:

To turn or bend aside; to deviate; to stray; to withdraw.

Examples:

"a line that declines from straightness"

"conduct that declines from sound morals"
Decline as a verb (transitive):

To refuse, forbear.

Examples:

"On reflection I think I will decline your generous offer."
Decline as a verb (transitive, grammar, usually of substantives, adjectives and pronouns):

To inflect for case, number and sometimes gender.
Decline as a verb (by extension):

To run through from first to last; to repeat like a schoolboy declining a noun.

Examples:

"rfquotek Shakespeare"
Decline as a verb (American football, Canadian football):

To reject a penalty against the opposing team, usually because the result of accepting it would benefit the non-penalized team less than the preceding play.

Reject as a verb (transitive):

To refuse to accept.

Examples:

"She even rejected my improved offer."
Reject as a verb (basketball):

To block a shot, especially if it sends the ball off the court.
Reject as a verb:

To refuse a romantic advance.

Examples:

"I've been rejected three times this week."

Reject as a noun:

Something that is rejected.
Reject as a noun (derogatory, _, slang):

An unpopular person.
Reject as a noun (colloquial):

a rejected defective product in a production line