chronology vs timeline

chronology and timeline both are nouns.

Word	Noun	Adjective	Verb	Adverb
chronology	Yes	No	No	No
timeline	Yes	No	No	No

As nouns, timeline is a hyponym of chronology; that is, timeline is a word with a more specific, narrower meaning than chronology:

chronology: a record of events in the order of their occurrence
timeline: a sequence of related events arranged in chronological order and displayed along a line (usually drawn left to right or top to bottom)

chronology (noun)	timeline (noun)
the determination of the actual temporal sequence of past events	a sequence of related events arranged in chronological order and displayed along a line (usually drawn left to right or top to bottom)
a record of events in the order of their occurrence
an arrangement of events in time