The national guard and the militia are not the same thing. The anti gun crowd always want to connect the two.
The National Guard is part of the militia.
Title 10, Section 311 (Dick Act) divides the militia into the organized militia (National Guard) and the unorganized militia (male adults not in the NG between 17 and 15, and younger than 65 for those who held a position as an officer.
There is also a Naval Militia, from which the US could get people to operate under letters of marque and reprisal.
The militia per Title 10, section 311 consists of the organized militia (national guard) and the unorganized militia.