patient vs sick person

patient and sick person both are nouns.

Word	Noun	Adjective	Verb	Adverb
patient	Yes	Yes	No	No
sick person	Yes	No	No	No

As nouns, sick person is a hypernym of patient; that is, sick person is a word with a broader meaning than patient:

Other hypernyms of patient include case, diseased person, sufferer.

patient (noun)	sick person (noun)
the semantic role of an entity that is not the agent but is directly involved in or affected by the happening denoted by the verb in the clause	a person suffering from an illness
a person who requires medical care

patient (adjective)	sick person (adjective)
enduring trying circumstances with even temper or characterized by such endurance