There is a big diference for a big reason.

24 bit rate file it's obviously a bigger file than 16 bit rate file. Why?
There is more information of each "take" of audio in '24. Then, if you going to apply a lot of changes, (adding effects, mixing, mastering, etc) a stronger file (24 bit) will respond better, without a high quality handicap.
Whatever, all audio files recorded in a cd (your final mix, i mean, your definite "song") shall be exported with 16 bit rate, 'cause an ordinary player can't play up to 16 bit rate files.

Ordinaries cd's contains files in 16 bit (Medonna, Eminem, The Postal service, whatever).

In that way, when i want record a guitar analog sound, y do it in 24 bit range, then, when i have the final mixing and mastering —the guitar, plus reason or other tracks, all handled in 24 bits— i export the result as aif or wav 16 bit file. alright?

greets!

Darbo

There is a lot of sites about mixing and mastering, over there i learned about this.