Cordelia was Leir's favorite. And if you go back to the original story, she did succeed him on the throne. So that's two more resemblances.
Well, no, and I misremembered this as well. Cordelia dies and never sits the throne.
I took a few moments and tried to sum up the two plots in three broad arcs (Acts II-IV in Lear are mostly political infighting and betrayers being betrayed, so I lumped them together).
[table="width: 750, class: grid"]
[tr]
[td]King Lear[/td]
[td]Storm King's Thunder[/td]
[/tr]
[tr]
[td]Lear decides to divide his kingdom amongst his daughters and holds a flattery competition. He awards his kingdom according to how well his daughters praise him. The eldest fawn, but the youngest blunts says she cannot compare her true admiration for Lear with anything else. Mistaking this, Lear rages and banishes Cordelia and splits his kingdom equally among the other two daughters.
The King of France still likes Cordelia, and agrees to still marry her even after being banished (they were betrothed)[/td]
[td]Ammun the All Father, God of Giants, decides giants ain't gianting well enough and breaks the ordning. The Giant begin to compete amongst themselves for place in whatever new ordning arises. An evil dragon takes advantage of the situation, allies with a Kraken, and then kills the storm giant queen and kidnaps the storm giant king. The storm giant king's youngest daughter has been named heir, and so ascends the throne in her father's absence. Her spoiled sisters work to try to take power for themselves, but have no idea about the dragon's plotting or even that there is a dragon, and so far have done little to weaken their sister.[/td]
[/tr]
[tr]
[td]Lear's sisters work to weaken Lear and manage to separate him from much of his support and drive him mad. Lear eventually reunited with Cordelia, now leading an invading French army. The other sister get up to shenangians with murder and sleeping around.
One is widowed, both are still struggling for power. The English nobles gather to fight off the French.[/td]
[td]Um... the party runs around the countryside and kills one or more giant lords that are doing bad things in the lords' quests to gain rank in the new ordning. The evil dragon manages the storm giant court from the shadows, making sure things stay unstable and the storm giants can't bring the other giant clans to heel. The two sisters play music for other giant lords and maybe plot and stuff -- not real clear here.[/td]
[/tr]
[tr]
[td]The French army loses, and Cordelia and Lear are captured. The sisters get betrayed, and die. Cordelia is executed. Lear dies of a broken heart. As is typical of Shakespeare's tragedies, pretty much everyone dies in the end. One of the surviving nobles takes the throne (and, interestingly, who it is varies by version -- that wily Bard, inventing alternate endings!).[/td]
[td]The PCs get to Maelstrom, meet some hill giant guards, the elder sisters try to bump them off (poorly), and then, maybe, learn of the kings abduction and out the evil dragon plotter. The PC then maybe rescue the King, or not, but the youngest daughter keeps the throne. Eventually, the PCs go fight the Dragon.[/td]
[/tr]
[/table]
There, quick and dirty, but that sums it up. If the adventure is based on King Lear, it's extremely superficial. Aside from a political entity in strife and the king having three daughters, there's just not much there.