As adverbs the difference between truthfully and faithfully
is that truthfully
is (manner) in a truthful manner while faithfully
is in a faithful manner.
In a faithful manner.
- The CD reproduces music faithfully.
(US) A conventional formula for ending a letter, used when the salutation addresses the person for whom the letter is intended using an honorific.
- I have been faithfully married for the past twenty years.
* (formula for ending correspondence) yours faithfully (UK)
* yours faithfully