phone bill vs telephone bill

phone bill and telephone bill both are nouns.

Word	Noun	Adjective	Verb	Adverb
phone bill	Yes	No	No	No
telephone bill	Yes	No	No	No

As nouns, phone bill and telephone bill are synonyms defined as:

phone bill and telephone bill: statement of charges for telephone service

phone bill (noun)	telephone bill (noun)
statement of charges for telephone service	statement of charges for telephone service