No, LFQW (linear fighters, quadratic wizards) specifically refers to the fact that in 3e (and maybe earlier editions to a lesser degree), wizards got more spells AND their existing spells got more powerful whenever they leveled up: thus, their power increased at a "quadratic" (geometric, exponential) rate. Fighters, on the other hand, got more powerful too, but at a linear rate. So a level 20 fighter might be 20x as powerful as a level 1 fighter, but a level 20 wizard was 20^2=400 times as powerful as a level 1 wizard. (Or so goes the argument; obviously the math for "class power" isn't that simple.)
That's bassically it, yes.
Let's suppose 2 classes, Mage and Thief.
At first level, the Thief can do several things:
1) acrobaticly jump around the battlefield
2) stealth and sneak
3) killing people with sneak attack of 1d6
4) skipping the HP with some sort of Knock-Out or Stun "trick"
On the other hand, the wizard can:
1) move around the battlefield with a spell (Jump, expeditious retreat, Spider Climb)
2) ignore HP with some spell (sleep, charm)
3) do damage (1d6 with shocking grasp)
4) do some utility stuff for the group (indentify magic items)
But, given levels, a linear Thief do the same things, only better. His Acrobatic skill goes through the roof, doing things that he couldn't do at lvl1. His damage increase with his sneak attack. His stealth stuff also increase, being able to surpass stronger sentinels (But as the high level sentinels are also better, it's kind of a treadmill), and his stunning ability becomes better.
On the other hand, the mage does not only get more damage, better divination spells, and stronger SoD spells. He also learn Invisibility, stepping on the Rogues toes. And he learn levitate, then fly, then dimiensional door, teleport and plane shift. He learn to summon monsters, Area of Effect Spells, protection stuff like Mirror Image, he learn to animate skeletons, summon walls, become ethereal....
So while the Thief gets, more or less, the same abilites, just they are more powerful, the Mage gets an increase in the power of his low level abilities, but also morea and more and more abilities. So assuming they were balanced at first level, they CAN'T be balanced at higher levels. Just like any two functions, one of them quadratic and the other being linear, can´t have the same values except in the point where they cross.
As long as some classes are quadratic, and some others are linear, they can't be balanced. The solution to this is either "nerf" the quadratic class, so it's linear, or "buff" the linear class, so it's also quadratic (for example, allowing the rogue to learn how to use traps, smoke bombs and caltrops, to *shadowstep*, to charm with his personality, to ignore hits through a "dodge" mechanics, to be able to recognize and dispell illusions, etc)
This will cause disgust in some people, no matter of what. If you nerf wizards, some people will dislike Mages being "dumbed down". If you buff Thieves, some people will dislke rogues being "too anime". And if you don't do anything, some people will dislke Mage being quadratic while thiefs are linear.