deletion vs aphaeresis

deletion and aphaeresis both are nouns.

Word	Noun	Adjective	Verb	Adverb
deletion	Yes	No	No	No
aphaeresis	Yes	No	No	No

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

deletion: any process whereby sounds or words are left out of spoken words or phrases
aphaeresis: (linguistics) omission at the beginning of a word as in `coon' for `raccoon' or `till' for `until'

Other hyponyms of deletion include apheresis, aphesis, elision, eclipsis, ellipsis.

deletion (noun)	aphaeresis (noun)
the act of deleting something written or printed	(linguistics) omission at the beginning of a word as in `coon' for `raccoon' or `till' for `until'
the omission that is made when an editorial change shortens a written passage
(genetics) the loss or absence of one or more nucleotides from a chromosome
any process whereby sounds or words are left out of spoken words or phrases