Thanks so much for your help and Sorry for the spelling mistakes
Language varieties is :
Idiolect: the person’s own language and vocabulary and way of speaking.
Dialect: A variety of language spoken in one part of a country –Regional- or by people belonging to a particular social class.
Accent: The way of pronouncing words in a particular region.
Slang: informal lexicon that have not gained widespread acceptability.
All of the above are relevant, but they are only a list of definitions of something else. If you are saying that, "The following are language varieties: idiolect, dialect, accent ...", then that is wrong. All of those things can distinguish one variety from another.
This is what does it mean for me language varieties, and for the main criteria of distinguishing a language from a dialect all what I know is that there is:
Vitality: the existence of living community of speakers.
This doesn't distinguish a dialect from a language. Do you mean that a language has vitality or that a dialect has vitality?
Historicity: It refers to a particular group of people find a sense of identity through using a particular language, it belongs to them.
This applies also to dialect.
Autonomy: a language must be felt by its speakers to be different from other languages.
This is more relevant. A person who speaks English believes they are speaking a different language from a person who speaks French; while a person who speaks Australian believes they are speaking the same language as someone who speaks British. This is a sign that Australian and British are both dialects of one language - English. (Or "Australian English" and "British English" to be more precise. But phrasing it that way makes it too easy to assign them both to the same langage.)