The main difference between Hazelnut and Acorn is that the Hazelnut is a nut of the hazel tree and Acorn is a fruit/nut of the oak tree.
The hazelnut is the nut of the hazel and therefore includes any of the nuts deriving from species of the genus Corylus, especially the nuts of the species Corylus avellana. It also is known as cobnut or filbert nut according to species. A cob is roughly spherical to oval, about 15–25 mm (0.59–0.98 in) long and 10–15 mm (0.39–0.59 in) in diameter, with an outer fibrous husk surrounding a smooth shell. A filbert is more elongated, being about twice as long as its diameter. The nut falls out of the husk when ripe, about 7 to 8 months after pollination. The kernel of the seed is edible and used raw or roasted, or ground into a paste. The seed has a thin, dark brown skin, which sometimes is removed before cooking.
Hazelnuts are used in confectionery to make praline, and also used in combination with chocolate for chocolate truffles and products such as Nutella and Frangelico liqueur. Hazelnut oil, pressed from hazelnuts, is strongly flavoured and used as a cooking oil. Turkey is the world’s largest producer of hazelnuts.
Hazelnuts are rich in protein, monounsaturated fat, vitamin E, manganese, and numerous other essential nutrients (nutrition table below).
The acorn, or oaknut, is the nut of the oaks and their close relatives (genera Quercus and Lithocarpus, in the family Fagaceae). It usually contains a single seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns are 1–6 cm (0.39–2.36 in) long and 0.8–4 cm (0.31–1.57 in) broad. Acorns take between 6 and 24 months (depending on the species) to mature; see the list of Quercus species for details of oak classification, in which acorn morphology and phenology are important factors.
The fruit of the hazel tree.
The fruit of the oak, being an oval nut growing in a woody cup or cupule.
A cone-shaped piece of wood on the point of the spindle above the vane, on the mast-head.