What is the difference between a perpendicular and a perpendicular bisector? 

Lines which intersect to form a right angle (90°) are known as perpendicular lines.

Example:

In the given figure, AB is perpendicular to CD. ∠AOC = ∠AOD = ∠BOD = ∠BOC = 90°.

A line p is said to be perpendicular bisector of another line segment AB, if p is perpendicular to AB and p bisects AB.

In the given figure, p ⊥ AB and p intersects AB in O such that  OA = OB.