From this this Taobao shop, here are the different ESP8266-based module pinouts and physical dimensions (and almost layout too ):
ESP-01
The most common module with printed PCB antenna:
- 2x4 2.54 mm pitch header
- built-in PCB-printed antenna
- 3 GPIOs: GPOI0/2/16
- UART URXD/UTXD
- RESET and CH_PD (powerdown)
- VCC/GND
- 14.2 mm W x 14.2 mm L
ESP-02
A less common module with antenna connector, that may be compatible with breadboards:
- Dual 1x4 2.54 mm pitch header in DIP form factor
- built-in U-FL connector for external antenna
- 2 GPIOs: GPOI0/2
- UART URXD/UTXD
- RESET and CH_PD (powerdown)
- VCC/GND
- 14.7 mm W x 14.2 mm L
ESP-03
A SMT (Sufrace Mount Technology) module with all pins broken out to castellated pads with built-in ceramic antenna:
- Dual 1x7 2 mm pitch castellated pads
- built-in ceramic antenna
- 7 GPIOs: GPOI0/2/12/13/14/15/18
- UART URXD/UTXD
- RESET and CH_PD (powerdown)
- VCC/GND
- 12.2 mm W x 17.4 mm L
ESP-04
Another SMT (Sufrace Mount Technology) module with all pins broken out to castellated pads without built-in antenna:
- Dual 1x7 2 mm pitch castellated pads
- external antenna on pad
- 7 GPIOs: GPOI0/2/12/13/14/15/18
- UART URXD/UTXD
- RESET and CH_PD (powerdown)
- VCC/GND
- 12.0 mm W x 15.0 mm L
ESP-05
A simple UART-only module with antenna connector:
- Single 1x4 2.54 mm pitch header
- built-in U-FL connector for external antenna *]No GPIO
- UART URXD/UTXD
- No RESET nor CH_PD (powerdown)
- VCC/GND
- 14.2 mm W x 14.2 mm L