TEDx has totally ruined the TED brand, Jen Brea did a genuine TED talk, any old fool can organise a TEDx event and pay a fee to license the name.
TEDx is a program which is run under the TED brand to bring a TED-like experience to as many people as possible. TED events are organised by the TED organisation themselves while TEDx events can be organised by anyone for their community after gaining a license from TED, hence "independently organised". TED provides a support system and very specific guidelines which need to be followed by the organisers.
There're just a couple of TED events which take place every year while over 10,000 TEDx events have taken place in all sorts of places since the program started in 2009. TEDx also has a global community of volunteer organisers and ambassadors who meet occasionally at special organiser events, the most recent of which was at TEDSalon Berlin.