what is the difference (if there is one)?
and if there is can i use string cleaner on a fretboard?
Well, the difference is that string cleaner is made to clean the dirt and grime that get on your strings while fretboard cleaner is meant to clean the dirt and grime that gets on your fretboard.

I wouldn't recommend using a string on a fretboard as it can potentially dry it out and damage it. I'd recommend something like this, which contains guitar polish, string cleaner, and fretboard conditioner: http://www.musiciansfriend.com/product/Gibson-Luthiers-Choice-3Pack-Cleaner?sku=420163
Breedlove Studio D25/SM Acoustic
Epiphone Les Paul Custom w/ EMGs
B-52 AT-212 Tube Amp
MXR 10 Band EQ
Digitech Bad Monkey
Boss RC-2 Loop Station
Is it okay if you use like a moist paper towel(moistened with water) on your fretboard?(sorry to hi-jack your thread)
unfortunately, water doesn't get on with timber.
Current Gear
Ibanez RG1570 - Going bye bye
Jackson DK2 - Eventually will be replaced with Maton Mastersound
Peavey valveking 212
Various EHX and Boss effects
ive never used a string cleaner, just take a towel and wipe off strings. fretboard conditioner is great tho
2006 Fender Deluxe Players Strat w/ Stephens Design Mojo pickups
Gibson SG Special
Carvin DC727 w/ Bareknuckle Nailbomb 7 and CWP 7
Mesa Boogie Mark IV head
Mesa Boogie 2x12 Cab MC90/EV200w

VP of Carvin Club but call me Il Duce