| Hardware and OS | LG K21 | Oppo A3s |
| Operating system | Android v9.0 (Pie) | Android 8.1 (Oreo); ColorOS 5.1 |
| Processor | Octa core, 2 GHz, Cortex A53 | Octa-core 1.8 GHz Cortex-A53 |
| Chipset | MediaTek Helio P22 | Qualcomm SDM450 Snapdragon 450 (14 nm) |
| GPU | PowerVR GE8320 | Adreno 506 |
| Architecture | 64 bit | |
| Internal memory | 32 GB | 16 GB, 2 GB RAM |
| External memory | Yes, Up to 1 TB | microSD, up to 256 GB (dedicated slot) |
| RAM | 3 GB | |
| Display | LG K21 | Oppo A3s |
| Type | IPS LCD | IPS LCD |
| Size | 5.7 inches (14.48 cm) | 6.2" inc |
| Resolution | | 720 x 1520 px |
| Touchscreen | Yes, Capacitive Touchscreen, Multi-touch | capacitive touchscreen |
| Screen-to-Body Ratio | | 81.2% |
| Screen format | 18:9 | |
| Display area | | 95.9 cm2 |
| PPI /points per inch/ | 282 ppi | |
| Display aspect ratio | | 19:9 (height:width) |
| Pixel Density | | 271 PPI |
| Colors | | 16M |
| Connectivity | LG K21 | Oppo A3s |
| 4G Bands | TD-LTE 2300(band 40), FD-LTE 1800(band 3) | |
| Network Support | 4G, 3G, 2G | |
| 2G Network | | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 |
| 3G Network | | HSDPA 850 / 900 / 2100 |
| SIM Slot(s) | Dual SIM, GSM GSM | |
| 4G Network | | LTE |
| Wi-Fi | Yes, Wi-Fi 802.11, b/g/n | Wi-Fi 802.11 b/g/n, WiFi Direct, hotspot |
| Network | | GSM / HSPA / LTE |
| USB Connectivity | Mass storage device, USB charging, microUSB 2.0 | |
| VoLTE | Yes | |
| SIM card | SIM1: Nano, SIM2: Nano | Dual SIM (Nano-SIM, dual stand-by) |
| Bluetooth | Yes, v5.0 | 4.2, A2DP, LE |
| Edge | | Yes |
| GPRS | | Yes |
| GPS | Yes with A-GPS, Glonass | Yes, with A-GPS |
| Speed | | HSPA 42.2/5.76 Mbps, LTE-A (2CA) Cat6 300/50 Mbps |
| USB | | microUSB 2.0, USB On-The-Go |
| Camera | LG K21 | Oppo A3s |
| Camera Setup | Dual | |
| Autofocus | Yes | |
| Camera Features | Digital Zoom, Auto Flash, Face detection, Touch to focus | |
| Flash | Yes, LED Flash | |
| Main camera | 16 MP, Primary Camera, 2 MP, | 13 MP, Dual |
| Image Resolution | 4616 x 3464 Pixels | |
| Specs | | 13 MP, f/2.2, AF
-2 MP, f/2.4, depth sensor |
| Video Recording | 1920x1080 @ 30 fps | |
| Features | | LED flash, HDR, panorama |
| Video | | 1080p@30fps |
| Selfie camera | 8 MP, Primary Camera, | 8 MP, Single |
| Multimedia | LG K21 | Oppo A3s |
| Headphone jack | 3.5 mm | |
| 3.5 mm Jack | | Yes |
| Loudspeaker | Yes | |
| Radio | | FM radio |
| Design | LG K21 | Oppo A3s |
| Colors | | Red, Dark Purple |
| Dimensions | | 156.2 x 75.6 x 8.2 mm |
| Weight | | 168 g |
| Battery | LG K21 | Oppo A3s |
| Capacity | 3200 mAh | |
| Type | Li-ion | |
| Removable | No | |
| Quick Charging | Yes, Fast | |
| USB Type-C | No | |
| Battery capacity | | 4230 mAh, Non-removable Li-Ion |
| Other features | LG K21 | Oppo A3s |
| Fingerprint Sensor | Yes | |
| Fingerprint Sensor Position | Rear | |
| Other Sensors | Light sensor, Proximity sensor, Accelerometer, Compass | |
| Other | LG K21 | Oppo A3s |
| Release date | | 2018, July |
| Sensors | | Accelerometer, proximity, compass |
