Clark Howard, who is famous for his radio show on saving money, often talks about the state guard.

https://clark.com/military/clark-howard-military-state-guard/

The definition of militia is handled a bit differently. There are rules on how they can (or can not) be structured and run. They can not be "organized", but can be like-minded people that gather for defense of the country/state/region. Training can not be structured as to be part of the militia, but individuals can work with each other to learn.

10 U.S. Code § 246 - Militia: composition and classes (a)The militia of the United States consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32, under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States and of female citizens of the United States who are members of the National Guard. (b)The classes of the militia are— (1)the organized militia, which consists of the National Guard and the Naval Militia; and (2)the unorganized militia, which consists of the members of the militia who are not members of the National Guard or the Naval Militia.