Thumb Bo
 

Is a Thmb BO and a Thumb BOLT the same or two different basses?

The BO stands for Bolt On. So yeah, it'll be the same

Correct. BO is just the abbreviation for Bolt-On

BO=Bolt On
NT=Neck Through (body)

For my two cents I also think the bodies are a smidgen different around where the neck meets the body. To me the NT looks wider and horns on the cutaway seem bigger/longer.

The posters above are correct - BO is Bolt On, NT is Neck Through. There are slight differences in the body shapes, as well - as socialleper pointed out. Please let me know if you've got any questions or need assistance in any way. Thanks!

HA! So I'm not crazy (or at least not wrong in this case.) They looked different in the pictures but I couldn't be sure. I thought it was an angle thing.
The NT looks like a more complete shape, where the BO looks stunted or something; under-developed.

I owned a Thumb B.O. and Ill tell you what-The tone wasnt stunted or underdeveloped! The thing was right and tight..Crisp Punchy articulate-I want another cuz I miss it...Still have my old Corvette and a bunch of Fenders but what a definitive tone those Thumbs have-and lighter than my passive 'vette..WARWICK!

I love both my '00 Thumb BO 5 and my '97 Thumb NT 5! What great tone I get from both.

Absolutely nothing wrong with a Bolt-On. BO's have a great punch and growl. My Thumb BO 6 is my go-to bass. Anytime I meet musicians, I receive many compliments on the sound. I decided that my Thumb will always be my introductory bass if/when I meet musicians for the first time.