destiny vs good fortune

destiny and good fortune both are nouns.

Word	Noun	Adjective	Verb	Adverb
destiny	Yes	No	No	No
good fortune	Yes	No	No	No

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

destiny: your overall circumstances or condition in life (including everything that happens to you)
good fortune: an auspicious state resulting from favorable outcomes

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

destiny (noun)	good fortune (noun)
an event (or a course of events) that will inevitably happen in the future	a stroke of luck
the ultimate agency regarded as predetermining the course of events	an auspicious state resulting from favorable outcomes
your overall circumstances or condition in life (including everything that happens to you)