Questions from guitar noob.
 

The Gibson also will have better woods (solid mahogany, with a solid maple top), binding over the fret ends (Gibson is one of the very few companies the does this), and a nitrocellulose lacquer finish.

Handmade in USA vs made/bodged together in China.
Go to the local guitar store and just pick them both up and compare. Even with no guitar expereince you should be able to see the difference in quality right away.
Test them un-amped to hear the natural sustain of the guitar. This will show the quality of the construction and the wood used.
What type of music are you interested in playing? There are other manufacturers of Les Paul style guitars with Gibson quality and better for less money. With Gibson you have to remember you are also paying for the name.

Mainly interested in Floyd, Zep, stuff like that. I immediately gravitated to a Strat, but it didn't quite feel right to hold. Looking for a first electric, but not necessarily looking for a depreciating beater that won't sound right.

I don't know. Still gathering ideas, and I'm not yet ready to buy anything, so there's lots of time.

Having just recently bought an Epiphone Les Paul, and being semi-experienced with decent guitar quality, I can tell you that my Epiphone, while not up to Gibson quality, is a solidly made and performing guitar for the money. If you're not interested or unable to spend in the 700USD on up range for a guitar, the Epiphone is a great option if you're looking for a Les Paul-style guitar. And you can always upgrade parts later if you decide you need to.