Skylark Dwarf, introduced in the late 60s by my father, was our first offering. This one was selected specifically as an ornamental, being shrubby and small (probably 10 at maturity) and having neat rows of branches set with equally neat rows of smallish leaves. It sets few, sometimes no fruits unless a different olive is nearby to act as a pollinator. Frantoio is a more conventional, broad-headed tree with somewhat pendulous branches. It sets a good crop of medium-sized black olives, good for eating and for their fragrant oil but obviously not so for sidewalks. Leccino is an even broader tree with typical foliage, except for the pale yellow undersides of the leaves. It sets a heavy crop of deep purple olives, prized for their oil, but only with another selection nearby. Pendolino has an attractive weeping habit and is a good pollinator for other olives. However, it needs cross-pollination with another selection to set its abundant but small, black fruits, which yield an excellent light oil. If you dont want the fruits, a successful strategy for all but Frantoio is to plant only the one cultivar and hope that your neighbor does likewise. Sun, reasonably well drained soil, only occasional watering when established (they are nearly as drought tolerant as our native oaks). Hardy to 15oF. or less.