The difference between Decline and Refuse

When used as nouns, decline means downward movement, fall, whereas refuse means collectively, items or material that have been discarded.

When used as verbs, decline means to move downwards, to fall, to drop, whereas refuse means to decline (a request or demand).

Refuse is also adjective with the meaning: discarded, rejected.

check bellow for the other definitions of Decline and Refuse

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.

Refuse as a noun:

Collectively, items or material that have been discarded; rubbish, garbage.

Refuse as a verb (transitive):

To decline (a request or demand).

Examples:

"My request for a pay rise was refused."
Refuse as a verb (intransitive):

To decline a request or demand, forbear; to withhold permission.

Examples:

"I refuse to listen to this nonsense any more."

"I asked the star if I could have her autograph, but she refused."
Refuse as a verb (military):

To throw back, or cause to keep back (as the centre, a wing, or a flank), out of the regular alignment when troops are about to engage the enemy.

Examples:

"to refuse the right wing while the left wing attacks"
Refuse as a verb (obsolete, transitive):

To disown.