fortune vs bad luck

fortune and bad luck both are nouns.

Word	Noun	Adjective	Verb	Adverb
fortune	Yes	No	No	No
bad luck	Yes	No	No	No

As nouns, bad luck is a hyponym of fortune; that is, bad luck is a word with a more specific, narrower meaning than fortune:

fortune: an unknown and unpredictable phenomenon that causes an event to result one way rather than another
bad luck: an unpredictable outcome that is unfortunate

Other hyponyms of fortune include mischance, mishap, even chance, toss-up, tossup.

As nouns, bad luck is a hyponym of fortune; that is, bad luck is a word with a more specific, narrower meaning than fortune:

fortune: your overall circumstances or condition in life (including everything that happens to you)
bad luck: an unfortunate state resulting from unfavorable outcomes

Other hyponyms of fortune include good fortune, good luck, luckiness, providence, ill luck, misfortune, tough luck, failure.

fortune (noun)	bad luck (noun)
an unknown and unpredictable phenomenon that causes an event to result one way rather than another	unnecessary and unforeseen trouble resulting from an unfortunate event
an unknown and unpredictable phenomenon that leads to a favorable outcome	an unpredictable outcome that is unfortunate
a large amount of wealth or prosperity	an unfortunate state resulting from unfavorable outcomes
your overall circumstances or condition in life (including everything that happens to you)