outflow vs leakage

outflow and leakage both are nouns.

Word	Noun	Adjective	Verb	Adverb
outflow	Yes	No	No	No
leakage	Yes	No	No	No

As nouns, outflow and leakage are synonyms defined as:

Other synonyms of outflow include escape, leak.

outflow (noun)	leakage (noun)
the discharge of a fluid from some container	the discharge of a fluid from some container
a natural flow of ground water
the process of flowing out