Legends Continuity: A fictional nomadic culture from the Star Wars Legends continuity, which includes figures like Boba Fett and Jaster Mereel. Mandalorians are a war-like culture who enjoy the thrill of battle and tend to uphold a code of honor that emphasizes loyalty to the tribe they belong to and to the one holding the title of Mandalore. They are not a species or race (though humans are the most populous members), and can consist of any race or species who joins and upholds the ways of the culture. They can often be identified by their armor or their emblem, a mythosaur skull.

Source: Mandlorian (Legends) article on Wookieepedia

Canon Continuity: A race of pacifistic humans from the planet Mandalore, introduced with established canon. Though once possessing a warlike past, Disney canon significantly watered down their importance to Jedi history and much of their culture with it.