First of all,hypersonic wind tunnel is basically a facility transfers high thermal energy to high kinetic energy. That means additional heating is required before the flow enters the nozzle.
The AEDC hypervelocity wind tunnel 9 is continuous wind tunnel with storage heating to promote the total temperature, while the JF12 is a pulsative shock tunnel that utilizes the gasdynamic compression of shock wave to create the high enthalpy and high pressure condition before the nozzle thoat. The former normally suffers from the insanely high expenses for construction, maintainance and every single test shot, with a gain of longer test time and better flow quality of course. The latter, on the other hand, costs much less (10% or less), especially for a detonation driving one, to fulfill the same test missions. And that makes a differnce with the chinese budget.
For shock tunnel, JF12 is definitely the biggest one in the world and the first to reach this big. By big, it includes both nozzle size and the length. The nozzle size is big enough to test a real size model which is important for hypersonic test for there is no available scaling criterion as that in low speed test. The lenght assures the test time of a shock tunnel which is a key concern to the force and moment measurement. In general, force measurement is not allowed in shock tunnel for its short duration, but that's ok for this JF12 becasue it has a test time of 100 ms. By first, I guess it also implies that JF12 is the only one in the world employs a reversely propagating detonation wave to drive the shock tube.
Hope it helps.