As a former National Guardsman:

1. The Guard has a dual role: the respond in times of crisis in the State (floods, tornadoes, riot, earthquake) and to be activated as part of the regular Army or Air Force in time of war. To that end they are trained in their federal role (e.g., as artillerists or quartermasters) AND in their state role (e.g., riot control training).

2. The Reserves (Army, Navy, Air Force, Marines, Coast Guard) have only a federal role and are only called to support State or civilian operations in extreme cases (e.g., an out of control wildfire); otherwise they train in their unit's speciality.

3. The individual ready reserve is composed of individuals who, although once trained in the Armed Forces, have for one reason or another been been seperated from the active reserve and are not assigned to a particular unit. These folks basically sit around until called up.

Hope this helps clarify the situation.