The difference is that they're using your data to target financial products at you (just like any other free service). But they don't sell your data at least.
The part you're missing is that as a part of the acquisition, Intuit was required by the Justice Department to divest the "tax" portion of Credit Karma - so no, they're not the same company. Credit Karma, the main app, is Intuit. The tax portion of Credit Karma is not.
The difference is that they're using your data to target financial products at you (just like any other free service). But they don't sell your data at least.