The difference between Decline and Worsen

When used as verbs, decline means to move downwards, to fall, to drop, whereas worsen means to make worse.

Decline is also noun with the meaning: downward movement, fall.

check bellow for the other definitions of Decline and Worsen

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.

Worsen as a verb (transitive):

To make worse; to impair.

Examples:

"The global warming has worsened the weather."
Worsen as a verb (intransitive):

To become worse; to get worse.

Examples:

"The weather has worsened."
Worsen as a verb (transitive, obsolete):

To get the better of; to worst.