For the most common usage the two terms are interchangeable. However, there is a technical horticultural difference. Because pecans are cross-pollinated (female flowers are pollinated with pollen from a different tree), every pecan seed is hypothetically genetically different. Thus, every tree grown from a seed (nut) is genetically unique and can be considered a variety. When a pecan variety is reproduced clonally by grafting, it is then a “cultivated variety” or cultivar. Cultivars are trees that have been selected, propagated, and given a name such as ‘Stuart’. Cultivars are usually perceived to have some advantageous characteristics for growth and nut production. All named pecan trees are actually cultivars, but they are often referred to as varieties.
Question answered by Dr. Randy Sanderlin, Pecan Research-Extension Station plant pathologist.