“Algonquin” and “Algonquian” are not synonyms. The Algonquians are one of the three Aboriginal linguistic families in Quebec. The Algonquin, who call themselves Anishinabeg, are one of the Nations that make up the Algonquian family. Their territory is in western Quebec in the Abitibi-Témiscamingue region; there are 9 communities there, along with one community in Ontario.
The Anishinabeg (Algonquin) are relatives of the Ojibwa, another nation that lives further south and west.
The Anishinabeg (Algonquin) language was used to name several places. One of the origins of the word “Québec” is the Algonquin word “kebec”, which means “where the river narrows”. However, there are other theories on the origin of this word and this is why specialists continue to study Aboriginal languages.