TL;DR: how the heck do I start getting one guitar's tone to sound more like another's?
Or, if it's easier to share, how did you go about finding your favorite tone?

I've been learning on an LTD viper-400 for the past few months, and then bought an epiphone SG g-400 recently because 1) I really, really, really wanted this look since forever; and 2) one finally popped up locally at a price point I've been waiting for.

Just talking about the difference when unplugged:

The epiphone sounds exactly how I've heard it in videos, but I didn't realize guitars could sound this different. I just like my viper's sound so much better, and... I'm ignorant enough to not know how to describe why. The SG just sounds... Airier? Lighter? The strings are definitely different. The sg has some smooth feeling to it, maybe because they're new strings, according to the seller. Do I just start with trying to figure my viper's string gauges or something and buy those for the SG? Though they both have almost the same low action, the strings on my viper feel more taught; might be just because of the jumbo frets, but is tighter-feeling strings a thing?

And when plugged in, I like each of their clean sounds, but favor the viper's a little more. I'm even less sure how to describe why or what the difference really is. Is there a process to fiddle with knobs? At what point do I start considering switching pickups? I can't tell what pickups the SG has, other than they're probably the originals. The viper's should be original too, seymour Duncan custom-5 (bridge) and jazz (neck) pickups.

Even though, generally, I've fallen in love with the viper, there isn't enough room in my home for two guitars at this time. That's a c/relationshipadvice issue, lmao. I'm keeping the ~~Homewrecker~~ iconic SG and selling ~~Sexy~~ my viper once I figure this out, and that's that. But yeah, tone. How does it work