Quote: "can you explain the diffrence between publishing trough TGC or not?"
The primary reason why a person may wish to publish through TGC would be if they are releasing to iOS/Mac but do not want to pay for the annual Apple developer license, or do not have access to a Mac to build and release their app. Apple charges $100 a year for the iOS developer license, and another $100 if you wish to publish to Mac.
However, if you already have the developer license and a Mac to build your app on yourself, there is no reason to go through TGC to release your app and you then have no other fees to pay other than what Apple takes out (30% of your sale total).
I'm not sure how well supported publishing through TGC is, if at all, as they do not have any solid information on the subject. I only know of one independent game that was published through TGC, and that was the winner of a Snake competition (MoonSnaker). The developer there ended up releasing it himself on some platforms as it was taking months for TGC to publish it after the competition ended.