deadly vs fatal

deadly and fatal both are adjectives.

Word	Noun	Adjective	Verb	Adverb
deadly	No	Yes	No	Yes
fatal	No	Yes	No	No

deadly (adjective)	fatal (adjective)
exceedingly harmful	bringing death
extremely poisonous or injurious; producing venom	having momentous consequences; of decisive importance
involving loss of divine grace or spiritual death	controlled or decreed by fate; predetermined
(of a disease) having a rapid course and violent effect	(of events) having extremely unfortunate or dire consequences; bringing ruin
causing or capable of causing death
of an instrument of certain death

deadly (adverb)	fatal (adverb)
(used as intensives) excessively
as if dead