What does ‘balance preamp’ mean?

Given your many posts I believe you would benefit from the purchase of Robert Harley's book 'The Complete Guide to High End Audio'.  Money well spent. 

No, a real balanced circuit is one where the positive (+), the negative (-) have distinct circuits, and negative is distinct from earth.So there is a higher manufacturing cost. There is also noise cancellation -- i.e. any noise common in both circuits is cancelled out -- hence, balanced is used in professional audio applications which are noisy environments.

^^ This. Its not hype- just better technology.

Given your many posts I believe you would benefit from the purchase of Robert Harley’s book ’The Complete Guide to High End Audio’. Money well spent.

THISSSSS!!!!!!!!!!!^^^^^^^^^^^!!!!!!!!Only don't just buy it- READ IT!

So what is a balanced vs unbalance preamp?
difference?

Unbalanced units are always on the verge of tipping over. They also require inordinate amount of aftermarket thingies for them to perform at their best.