A diode array is a bank of many diodes. Each of these diodes cause electricity to flow in one direction. In the case of diodes which are sensitive to light, these diodes are termed photo diodes, hence the detector is a photodiode array detector (PDA).
In HPLC Diode array detector (DAD) is a colloquial term for a PDA, it does not specify the parameter which causes the electricity to flow.
The WaveQuest uses a different type of technology, which involves dynamic Absorbance detection technology, hence the term dynamic Absorbance detector (DAD). I am sorry, but the details of that technology are company confidential.