Nucleophilicity vs Basicity
by definition a nucleophile, is a lone pair donor. phile meaning 'loving'. i.e its attracted to species which are electron deficient. the term is used to describe a species in an organic mechanism.a  bronsted base, is a proton accepter. Mostly in organic chemistry, you draw curly arrows, going from the nucleophile to electrophiles,most usually a electron deficient carbon. so it acts more as a Lewis base. which is a lone pair donor. however there are protons floating around in most organic reactions, also very electronegative atoms such the halogens(leaving groups). which pick up protons so i guess by defintion you could say they act as bonsted bases as well as nucleophiles. However the term nucleophile is mostly reserved for the species acting on the electrophile in an organic mechanism.