Green Lanterns

[Stagier]

I don't really read DC books, I have a general idea as to who is whom but not in much detail.

Could anyone differentiate the Lanterns for me?

Isn't there one per universe? or planet? How come earth has 5, not including jade. How is Hal back, looks de-aged and not the spectre?

Thanks in advance.

[Stagier]

Nevermind, found an old thread.

Thanks