ATmega328P instead of the slightly larger and more common QFP (quad flat pack). The other difference is that it uses a crystal oscillator instead of a smaller resonator. Crystal oscillators are more accurate, which is useful if you need accurate time keeping. The board came with no documentation, so I assumed it would work like a standard Arduino Pro Mini.
After opening the package I just soldered on the 90 degree header for the serial connections, then connected it into a PL2303HX USB-TTL adapter. The red power LED came on, and the blue LED started flashing - indicating the pre-loaded blink sketch was running. The blue LED is quite bright, even though it uses a 750 Ohm current-limiting resistor. I selected Pro Mini 5v @ 16Mhz from the Arduino IDE, pressed reset, and tried uploading a test sketch. Avrdude timed out, so I tried again. There was only one quick blink of the LED - indicating a short timeout for the bootloader. In case the board was using optiboot @ 115,200kbps, I changed the upload speed in the boards.txt file, and tried a few more times but still no luck.
I decided to flash a new bootloader so I'd have a known configuration. I chose the Uno from the boards menu because it's configuration uses the optiboot bootloader @ 115,200kbps. I connected my USBasp, selected USBasp from the programmer menu, then selected "burn bootloader".
2014/09/22 update:The Pro Mini boards are now selling for $2.50 or less on Aliexpress, so I picked up another one. This time I checked the fuse settings with avrdude:
avrdude.exe: safemode: Fuses OK (E:05, H:DA, L:FF)
The bootsz fuse is 01, which is 2Kbyte (1Kword), which confirms they do not come with optiboot flashed (which is only 512 bytes).