There are several ESP-12 modules: some have 16 pins, some have 22 pins: technically these modules are identical, the only difference is that the SPIHD pins are available on the 22 pin versions.
All ESP8266's use the same OS and can be flashed with the same homebrew firmware (eg. Arduino) if the flash memory is large enough, but with some modules (eg. an ESP-01) you only have physical access to a limited number of pins.
See more about the ESP (the single chip and the modules) in our Wiki-pages.
Because you're saying your module has 30 pins, I'm guessing you actually have a NodeMCU, which is a development board built around an ESP-12.