Another device - another principle?

Hello. In addition Thoughtstream I also bought another device biofeedback neurosky mindwave mobile works on the principle of the EEG.
But I do not quite understand - the same principle that works and Thoughtstream? I put sensors neurosky mindwave Mobil to fingers and hands had on the monitor readings are the same as from applying to the sensor head. As I understand it is the same principle of galvanic skin response or is it something else?
If the sensors are attached to the head Thoughtstream it will EEG device? Explain to me - I'm completely confused.

EEG reads the level (voltage) of electrical signals with the brain. (brainwaves) Biofeedback reads the electrical resistance between the 2 electrodes on the hand sensor. It passes a small amount of current through the skin. When the skin is wet the resistance is low (current flows better through a wet surface). When the skin is dry the resistance increases.

No the ThoughtStream cannot act as an EEG.