Space science, not space magic.

The Lanterns (of all colors) derive their power from the emotions, which manifest in different color light. The Greens run on Willpower. All willpower is channelled into the Central Battery, which in turn powers smaller batteries, which powers rings. The rings have to be charged once a day, or whatever the galactic equivalent is. Despite being called batteries, they more closely resemble handheld lanterns.

Thanks Tupka, for answering my first question 🙏

Different creators and different methods. The Green rings were made by the self proclaimed Guardians using Science. The Red Rings were made by Atrocitus with Blood Magic. The Yellow rings by the weaponers of Qward in a more "Blacksmith" way.

They also can be charged in different ways. Soranik for example, learned how to charge her yellow ring without the need of a battery by using fear, my guess is that other ring users may be able to do something similar if they acquire enough mastery of the emotion.

SA Hal threw the term “magic ring” around a few times. Science being indistinguishable from magic and whatnot. Hal also made is GL outfit and wore it under his civilian clothes originally. The suits and constructs came later. The constructs just cover their civilian clothes instead of the other way around.