What distinguishes albuminous seeds from non-albuminous seeds?  

Albuminous seeds have a residual endosperm, while non-albuminous seeds do not.

Albuminous seeds are found only in legumes, while non-albuminous seeds are found in cereals. 

Non-albuminous seeds contain a part of the nucellus, known as perisperm, while albuminous seeds do not. 

Non-albuminous seeds have two cotyledons, while albuminous seeds have one.