The difference between Ill and Poorly

When used as adverbs, ill means not well, whereas poorly means in a poor manner or condition.

When used as adjectives, ill means evil, whereas poorly means ill, unwell, sick.

Ill is also noun with the meaning: trouble.

check bellow for the other definitions of Ill and Poorly

Ill as an adjective (obsolete):

Evil; wicked (of people).
Ill as an adjective (archaic):

Morally reprehensible (of behaviour etc.); blameworthy.
Ill as an adjective:

Indicative of unkind or malevolent intentions; harsh, cruel.

Examples:

"He suffered from ill treatment."
Ill as an adjective:

Unpropitious, unkind, faulty, not up to reasonable standard.

Examples:

"'ill manners; ill will"
Ill as an adjective:

Unwell in terms of health or physical condition; sick.

Examples:

"I've been ill with the flu for the past few days."
Ill as an adjective:

Having an urge to vomit.

Examples:

"Seeing those pictures made me ill."
Ill as an adjective (hip-hop slang):

Sublime, with the connotation of being so in a singularly creative way.
Ill as an adjective (slang):

Extremely bad (bad enough to make one ill). Generally used indirectly with to be.

Examples:

"That band was ill."

Ill as a noun (often [[pluralize]]d):

Trouble; distress; misfortune; adversity.

Examples:

"Music won't solve all the world's ills, but it can make them easier to bear."
Ill as a noun:

Harm or injury.

Examples:

"I wouldn't want you to do me ill."
Ill as a noun:

Evil; moral wrongfulness.
Ill as a noun:

A physical ailment; an illness.

Examples:

"I am incapacitated by rheumatism and other ills."
Ill as a noun (US, slang):

PCP, phencyclidine.

Poorly as an adverb:

In a poor manner or condition; without plenty, or sufficiency, or suitable provision for comfort.

Examples:

"to live poorly"
Poorly as an adverb:

With little or no success; indifferently; with little profit or advantage.

Examples:

"to do poorly in business"
Poorly as an adverb:

Meanly; without spirit.
Poorly as an adverb:

Without skill or merit.

Examples:

"He plays tennis poorly."