The thing is, I don't think you can really compare the movies.
Sure, they both are in CGI, and they both have a heroine who grew up in isolation, unable to leave their small space (Rapunzel and Elsa). And a lot of people say that they're alike.
But I find them to be so fundamentally different that I can't process comparing them.
Tangled is about a girl who has power and can control her power but she's so deceived and imprisoned that she's powerless. She accepts her prison because she can't see the bars. But finally she has a dream and she is so into this dream that she is willing to breach the prison, so when the opportunity literally drops into her lap in the form of a bad boy, she takes it. Only when she gets out into the world does she realize that the world is so much bigger than her prison and life is so much more complicated than what her keeper tries to make it out to be. She doesn't even realize it's a prison until she's dragged back into it, but this time she has the strength to go up against her warden.
Frozen is about two sisters who were inseparable until an accident forced a wall between them. The elder is powerful, because shew knows she has power and she fears it, so because she's so afraid of herself she can't control it. The younger suffers from the elder's voluntary banishment as well, because she's starved for love and protection and attention, to the point of becoming almost desperate for it. So when they are reintroduced to the world, the elder can't handle it and the younger is so excited she abandons her wits and goes looking for love in all the wrong places, turning into a big fight and catastrophe. The younger tries to repair the disconnect, but the elder is relishing in the new found freedom of not having to conform to the bonds and please everyone, and is afraid of returning to that state so she lashes out, breaking the bond further. Things escalate and the younger is left in the place of the elder, forsaken, afraid and alone. The elder meanwhile is experiencing her worst nightmare, and both sisters almost don't have the strength to go on, but the elder manages to save the younger from her betrayer.
So in essence, Tangled is about self-discovery and independence. Frozen is about two sisters and just how much trust and distrust can harm. There are some similarities - the unlikely love, the betrayel of someone you trusted and thought you loved - but on the whole I think they're two completely different stories and so can't be compared in that way.
