Ranger Wickett beat me to it. Harry Potter is a very good example. There is no balance.
I don't know Harry Potter, but the Wizard of Earthsea provides an interesting variant on this.
Earthsea wizards are extremely powerful magical generalists. Sparrohawk, as a newly-minted sorceror, is able to take down multiple young dragons in a very short space of time by binding their wings with his magic (a literary example, by the way, of dragon minions). As well as this pretty good battle magic he can summon the weather, transform into a bird, hold a boat together by magic, suppress the power of evil spirits, etc. At least a mid-to-high level AD&D spell user (but without fireball or disintegrate).
However, for various reasons that are a bit obscure in the original trilogy, but are introduced with a degree of retconning in the very different fourth book (Tehanu?), wizards have a very limited worldly role and hence only exercise limited worldly power.
So a game modelled on Earthsea might work well if something like HeroWars/Quest was used as the system - wizards would be low on relationships, whereas warriors (who in Earthsea would be heroic nobles like the prince in the third book) would have lots of relationships and similar worldly connections on which to draw. Part of a warrior's strength would be his/her embeddedness in the community.
On the other hand, in a game modelled heavily on personal action-adventure heroism (like D&D), and hence in which the community tends to be a backdrop rather than a central feature of the situation, then I don't think Earthsea would work. You'd have to go to something like Conan, using metagame mechanics (in the form of AD&D hit points, or 4e powers, or whatever . . .) to achieve balance.
Which takes me to:
I posited that spellcasters should be more powerful, but non-spellcasters should be able to twist the threads of fate in some way.
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In terms of story, I think the difference boils down to the Heroic Act. Spellcasters wield raw power - they cast bolts of lightning or divine strikes from above to devastating effect, or they use their magic to strange and powerful effects or healings. But they don't, or rarely, make a Heroic Act - which is exemplified by Conan tossing that dagger
Arguably, this
is the 4e approach - arcane PCs use powers that are more-or-less simulationist or "fiction first" in interpretation (ie the mechanical features of the power is a model of the ingame command of arcane forces) whereas martial PCs use powers that have a heavy metagame or "rules first" aspect (ie the mechanical features of the power are not just a model of the ingame sword stroke or dagger throw, but also of there occuring a constellation of luck, heroism etc that means taht the sword stroke or dagger throw is a crucially telling one).
all strikers are basically the same, just with different fluff
Not my experience (eg elf ranger plays differently from half elf feylock plays differently from drow sorcerer). YMMV, and apparently does.