See http://www.mathworks.com/help/techdoc/ref/lt.html and http://www.mathworks.com/help/techdoc/ref/gt.html
An evaluated expression is true when the result is nonempty and contains all nonzero elements (logical or real numeric). Otherwise, the expression is false.
So when you have
if A < B
and A or B is a vector (or a matrix) then the "if" is only considered true if all A < B are true.
