Both smartphones comes with Metal body and Fingerprint Scanner. Oppo A57 has a 5.2-inch (1280 x 720 pixels) HD 2.5D curved glass display where as Oppo F1s comes with higher 5.5-inch (1280 x 720 pixels) HD IPS 2.5D curved glass display with Corning Gorilla Glass 4 protection. A57 is powered by a 1.4GHz Octa-Core Snapdragon 435 processor , Oppo F1s is powered by a 1.5 GHz Octa-Core MediaTek MT6750 64-bit processor. Both devices are coupled with 3GB of RAM and 32GB of intrenal storage which is further expandable up to 128GB.
Coming to camera both phones has  a 16MP front facing camera and 13MP rear camera. Connectivity options include 4G VoLTE, WiFi 802.11 a/b/g/n (dual-band), Bluetooth 4.1, GPS. Oppo F1s is packed by a 3075mAh Battery where as Oppo A57 comes with smaller 2900mAh battery.
Oppo A57 Vs Oppo F1sÂ
| Display :5.2-inch (1280 x 720 pixels) HD 2.5D curved glass display | Â 5.5-inch (1280 x 720 pixels) HD IPS 2.5D curved glass display with Corning Gorilla Glass 4 protection |
| CPU: Â 1.4GHz Octa-Core Snapdragon 435 processor | 1.5 GHz Octa-Core MediaTek MT6750 64-bit processor |
| Adreno 505 GPU | Mali T860 GPU |
| RAM Â 3GB RAM | Â 3 GB RAM |
| ROM  32 GB internal storage ,  microSD card support up to128GB |  32GB internal memory, expandable memory up to 128GB with micro SD |
| Camera : 13MP rear camera with f/2.2 aperture, 5P lens, PDAF, LED Flash | 13MP rear camera with LED Flash |
| 16MP front-facing camera with f/2.0 aperture | 16 MP front-facing camera , Beautify 4.0,Screen Flash ,Various Filters |
| 4G VoLTE, WiFi 802.11 a/b/g/n (dual-band), Bluetooth 4.1, GPS | 4G VoLTE, WiFi 802.11 a/b/g/n (2.4GHz + 5GHz), Bluetooth 4.1, GPS, USB OTG |
| Â Fingerprint Scanner | Fingerprint Scanner |
| Battery 2900mAh battery | Â 3075mAh battery |
| OS- Android 6.0.1 (Marshmallow) with ColorOS 3.0 | Â ColorOS 3.0 based on Android 5.1 (Lollipop) |
| Dimensions: 149.1×72.9×7.65mm; Weight: 147g | Dimensions: 154.5 x 76 x 7.38mm; Weight: 160g |
OPPO A57 comes in Gold and Rose Gold colors, is priced at 1599 yuan (US$ 230 ) where as Oppo F1s is now available in India for Rs  16,990. Both devices has similar specs Oppo A57 has a better  processor compared to Oppo F1s and smaller display.