Biosurfactants are molecules capable of reducing surface tension. Some of them are good emulsifiers (e.g. Rhamnolipids). Bioemulsifiers are molecules capable of emulsifying immiscible phases. It all depend on their functionality - in which task they are good.    

Biosurfactants are always bioemulsifiers, but some biopolymers might be emulsifiers but not considered surfactants. Acacia gum is a popular emulsifier in beverage industry but reduces surface and interfacial tension only moderately. It has to be said that there is no clear line between both.

I am not completely agree with Titus! Some biosurfactants are not bioemulsifiers. One thing is that biosurfactants reduce the surface tension much more than bioemulsifier.

I am agreed with Thavasi Renga Thavasi