Basically, the big picture includes your guitar->connection to effects system->Pre Amplifier Effects (not preamp - more as in, before the amplifier), Amplifier itself (not including the speaker), the effects that come after it (either in a "dummy load" configuration ala. Eddie Van-Halen circa 1978, or me running digital effects within the amp that come before the power-amp and speakers), the "power amp" (if not doing a entirely pre-amplifier effects configuration like I used to use), then the speakers. And all of this stuff makes a differenfce in sound, but how much? And what is most important, and what is not.

Outside of gear, the major big picture is most likely, except in rare cases, you are playing as a part of a BAND, and certain details dissappear or become far less important once you add bass, drums, and vocals are added, and the mics, producer, engineer, and whatnot, are included. It's realy easy for guitarists to get caught up on these tiny nuances that are the most important.

Another big picture item to mention is brand names really don't matter that much in the ways of sound unless you're wanting to follow some kind of corporate cookie-cutter thing, which as I recall, is something us musicians are supposed to be rallying against rather than conforming to. Brands really don't mean shit. Most of the guitars I play are my own builds, a couple of my pedals are home-brew, and my brands are a mix of Berhinger, BOSS, EHX, Fender, Kramer, and Line6 Gear anyway. Some people become so brand loyal all they are focusing more on being a part of a lifestyle, than being a musician. The "Gibson Man" in a Gibsonm cap talking about all the great guys who played a Gibson is probably more about what the brand name means in terms of social acceptance, rather than that they have a good guitar.

• the player - first off is the player. Everyone has a different genetic makeup, and that does influence how you play, or how you learn to play, and how you naturally are the most comfortable. This is a very complex variable that involves everything from genetics to experience, and all points in between without any singular one taking priority over the other.
• the guitar - the guitar itself is another complex series of variables, which I will break down elsewhere. Guitarists (and the companies they cater to) are so full of truth and crap it's hard to separate the two. Everything from "tone woods" all the way the pickups you use are hotly debated. I'd say at the least important would be things like the finish and wood species, with the most important elements being the scale length, bridge system, and pickups.
• the effects pre-amplifier - ie, the classic stompbox method most of us are used to using after awhile, where we stack pedals in front of the amplifier ala Kurt Cobain's methods (or any grunge band really). Like guitars, a whole lot of marketing fluff and superstition confused for truth.
• the amplifier - The amplifier itself is not much unlike the guitar and pedals. However, it has a higher importance (in a lot of ways) compared to the stuff behind it since it sets the basic sound that's going to be manipulated from what comes after it, and it's going to color anything that came before it.
• effects post-amplifker - in a digital rig or "dummy load" setup (where the amplifier is given a "dummy load" in the form of transformers placed where teh speaker cab goes before hitting a separate power amp), effects come after the amp, and before the speakers to give them a more vibrant sound...particularly modulation, reverb, and delay effects. There's a reason what Edward Van-Halen did with his plexi was so revolutionary - and this was one of those things. Prior to this, people had to rely on getting those effects in the studio, and then do without live (which lead to a lot of complaining from listeners about that "Cool sound" that couldn't be replicated from the 80's on back).
• power-amp - The power amp's job is miniscule in the effect of tone, this is why I laugh a bit when people talk about power tubes, they have a minor effect, mostly on bass and treble frequencies, but it's not a killer, since a lot of the effects of the power-amp can be EQ'd out.
• speakers - Possibly one of the biggest parts of how sound is effected. Size, construction, magnet size/strength, and wirings all effect what comes out of the end. This is also one of the most neglected parts of the rig, in part because it's not something people see. It's hidden in the back of a wooden box behind the grillcloth.

One thing that might help some beginners is knowing that what sounds good in the bedroom standalone won't sound good in a studio setting. A guitar is a Midrange instrument, hence why midrange is a big thing in guitar tone. What did it a disservice was the 90's and 2000's where we had a lot of guitarists with big fat fuzz pedals (grugne bands), stacked distortion pedals (Buzz Osbourne, again Alt-rock, or Dimebag Darrel in heavy metal), and these tones were often mixed up by the amateur guitarist with the bass, but also lead to previous generations creating some kick-ass tones. Thing is though, guys like Buzz Osbourne or Dimebag knew what the hell they were doing to get a good sound, and there's a LOT more midrange in their signal that it seems like. The whole "Scooped Mids" thing that started around the time was perpetuated by high school would-be guitarists who were not yet ready to learn what E.Q. is.