Although similar in shape and buttery goodness, the hazelnut and macadamia nut are quite distinct. Sometimes called filberts or cobnuts, hazelnuts originated in Asia, while macadamias hail from Australia. Hazelnuts are a true nut in the botanical sense, while macadamias should really be classified as a seed. Their flavors are similar, with the taste of a hazelnut resembling a cross between almonds and macadamias.
Macadamias make a suitable substitute for chopped hazelnuts in cookies or breads. If your recipe calls for hazelnut butter or ground hazelnuts, subbing in macadamias may change the outcome of the dish because of their higher fat and lower protein content. Macadamias also come with a higher price tag, so using them in lieu of hazelnuts could raise your grocery bill. Use either or both nuts, roasted, as a garnish for salads, mixed with breadcrumbs to make a crust for fillets of fish or chicken or as an addition to stuffing or rice pilaf.
References and ResourcesFastachi: Hazelnuts/Filberts
Fastachi: Macadamia Nuts
ASU School of Life Sciences: Is a Macadamia Nut Really a Seed, or a Nut?
University of Nebraska-Lincoln Extension: Nuts for Nutrition
The Cook's Thesaurus: Nuts
Organic Authority: How to Use Hazelnuts, Macadamias, Pistachios and More Nut Recipes for Autumn