Differences between National Guard and Army Reserves?

Funding, chain of command, and area of responsibility.
For funding, NG gets State funds where Reserves does not. For Chain of Command, the NG has the State Governor in their Chain and the Reserves does not. NG is called up for State emergencies while the Reserves does not.

The main difference is the National Guard is a state organization, and not falls only under the command of the POTUS, but also under the direction of the governor. You can be federally activated, and activated by the state. Examples of state activation include flood relief, hurricane relief, support and rescue responses, or civil disturbances if there turned out to be major rioting or civil unrest. If you are state activated, you do NOT get paid at the same level as a Federal Activation, which is paid by rank and time in service pay grid. I am NOT certain if states have different levels of pay, but for state activation you make less money. You and your unit fall under the control of the state's adjutant general also referred to as the TAG. The reserves are Federal ONLY. You can be activated only under the direction of the Dept. of Defense with the authority of the POTUS. They do NOT respond to local disaster response under the direction of the governor or the TAG. There are generally better benefits given by the state for serving in the National Guard, but each state has it's own benefits, and you'd have to look that up. The Reserves are broken and have been for a long time. Their budget and organization is flawed, and it's just horrible, and you get fewer benefits with the reserves, and none of them from the state. If you're inquiring for joining, I highly recommend the GUARD over the reserves, and would venture to say - DO NOT JOIN THE RESERVES. The only exception is, the Guard has only Army and Air Force, but all five branches have reserves, so if you're thinking Coast Guard, Marine, or Navy, you have no choice.

Guard is for us. Reserves can go anywhere