I'm assuming you are referring to the option "Real cases" in the Case Library?
"Real cases" refer to cases that consulting firms have provided us with. On the top right you will see the logo of the consultancy that has given a case they have used in the past to PrepLounge (e.g. Bain Case: Old Winery, Oliver Wyman Case: On the right track, Roland Berger Case: OnlineStar etc.). We at PrepLounge work closely together with top consulting firms to make the interview process more transparent for you and give you the best practice material you will find.
The other cases are PrepLounge cases. They are not inferior in quality, they just don't directly/officially come from companies.
As the other experts stated, for your practice it does not really matter which case you use. If you prepare for the specific company, it makes sense to go through their company case, but even more important is that you get HOW to solve cases in general.
Hope this helps!
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