Providing for the needs of an unprotected person that lacks resourcesfor his/her own support in modern society, asks for a new legal patternof maintenance. This new way other than the traditional of family-origin,brings a broader point of view with it. Is named personal maintenance private-law relationship. Despite legal or contractual origin, the nature of the reciprocal and previous vinculum between obligor and obligee, is the critical element in order to delimit and distinguish the legal frame work of two institutions with very similar configuration but otherwise fully autonomous: family-origin maintenance and contractual maintenance. This paper aims to give an overall view of the identifiable theoretic differences between themSe analiza la pensión alimenticia entre parientes y el contrato de pensión alimenticia como expresión típica de los alimentos extraparentales. A identificar las diferencias técnicas entre una y otro, está dirigido el presente trabajo.