| Hardware and OS | Nokia C21 | Oppo A3s |
| Operating system | Android 11 (Go edition) | Android 8.1 (Oreo); ColorOS 5.1 |
| Processor | Octa-core (4x1.6 GHz Cortex-A55 & 4x1.2 GHz Cortex-A55) | Octa-core 1.8 GHz Cortex-A53 |
| Chipset | Unisoc SC9863A (28nm) | Qualcomm SDM450 Snapdragon 450 (14 nm) |
| GPU | IMG8322 | Adreno 506 |
| Internal memory | 32GB 2GB RAM, 32GB 3GB RAM, 64GB 3GB RAM | 16 GB, 2 GB RAM |
| External memory | microSDXC (dedicated slot) | microSD, up to 256 GB (dedicated slot) |
| Display | Nokia C21 | Oppo A3s |
| Type | IPS LCD | IPS LCD |
| Size | 6.52 inches, 102.6 cm2(~77.5% screen-to-body ratio) | 6.2" inc |
| Resolution | 720 x 1600 pixels, 20:9 ratio | 720 x 1520 px |
| Touchscreen | | capacitive touchscreen |
| Screen-to-Body Ratio | | 81.2% |
| Display area | | 95.9 cm2 |
| Display aspect ratio | | 19:9 (height:width) |
| Pixel Density | | 271 PPI |
| Colors | Dark Blue, Warm Gray | 16M |
| Connectivity | Nokia C21 | Oppo A3s |
| 2G Network | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 (dual-SIM model only) | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 |
| 3G Network | HSDPA 850 / 900 / 2100 - International | HSDPA 850 / 900 / 2100 |
| 4G Network | LTE | LTE |
| Wi-Fi | | Wi-Fi 802.11 b/g/n, WiFi Direct, hotspot |
| WLAN | Wi-Fi 802.11 b/g/n, hotspot | |
| Network | | GSM / HSPA / LTE |
| SIM card | | Dual SIM (Nano-SIM, dual stand-by) |
| Bluetooth | 4.2, A2DP | 4.2, A2DP, LE |
| NFC | No | |
| Edge | | Yes |
| GPRS | | Yes |
| CDMA | HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100 - LATAM, Brazil | |
| GPS | Yes, with A-GPS | Yes, with A-GPS |
| Speed | HSPA 42.2/5.76 Mbps, LTE Cat4 150/50 Mbps | HSPA 42.2/5.76 Mbps, LTE-A (2CA) Cat6 300/50 Mbps |
| Technology | GSM / HSPA / LTE | |
| USB | microUSB 2.0 | microUSB 2.0, USB On-The-Go |
| Main Camera | Nokia C21 | Oppo A3s |
| Camera | 8 MP | |
| Features | LED flash, HDR | |
| Video | 720p@30fps | |
| Camera | Nokia C21 | Oppo A3s |
| Main camera | | 13 MP, Dual |
| Specs | | 13 MP, f/2.2, AF
-2 MP, f/2.4, depth sensor |
| Features | | LED flash, HDR, panorama |
| Video | | 1080p@30fps |
| Selfie camera | | 8 MP, Single |
| Selfie camera | Nokia C21 | Oppo A3s |
| Camera | 5 MP | |
| Features | LED flash | |
| Video | 720p | |
| Multimedia | Nokia C21 | Oppo A3s |
| 3.5 mm Jack | Yes | Yes |
| Radio | FM radio | FM radio |
| Loudspeaker | Yes | |
| Design | Nokia C21 | Oppo A3s |
| Body build | Glass front, aluminum frame, plastic back | |
| SIM | Single SIM (Nano-SIM) or Dual SIM (Nano-SIM, dual stand-by) | |
| Colors | | Red, Dark Purple |
| Dimensions | 169.9 x 77.9 x 8.8 mm (6.69 x 3.07 x 0.35 in) | 156.2 x 75.6 x 8.2 mm |
| Weight | 195 g (6.88 oz) | 168 g |
| Features | Nokia C21 | Oppo A3s |
| Sensors | Fingerprint (rear-mounted), accelerometer, proximity | |
| Battery | Nokia C21 | Oppo A3s |
| Type | Li-Ion 3000 mAh, removable | |
| Battery capacity | | 4230 mAh, Non-removable Li-Ion |
| Other | Nokia C21 | Oppo A3s |
| Release date | | 2018, July |
| Sensors | | Accelerometer, proximity, compass |
