A build is a particular construction of a character in game mechanical terms. It usually refers to a choice of class, various optional traits, and a specific set of tactics or character goals. For instance, a spiked chain wielding fighter is a specific kind of fighter who takes feats to optimize his use of that weapon.
Builds don't usually refer to point-based characters. Instead, the term might be used to refer to a construct such as a specific power. However, the build is still used as a verb to describe creating a character in mechanical terms.