| Hardware and OS | vivo Y51 | Oppo A3s |
| Operating system | Android 5.0.2 (Lollipop); Funtouch 2.5 | Android 8.1 (Oreo); ColorOS 5.1 |
| Processor | Quad-core 1.2 GHz Cortex-A53 | Octa-core 1.8 GHz Cortex-A53 |
| Chipset | Qualcomm MSM8916 Snapdragon 410 (28 nm) | Qualcomm SDM450 Snapdragon 450 (14 nm) |
| GPU | Adreno 306 | Adreno 506 |
| Internal memory | 16 GB, 2 GB RAM | 16 GB, 2 GB RAM |
| External memory | microSD, up to 256 GB (dedicated slot) | microSD, up to 256 GB (dedicated slot) |
| Display | vivo Y51 | Oppo A3s |
| Type | IPS LCD | IPS LCD |
| Size | 5" inc | 6.2" inc |
| Resolution | 540 x 960 px | 720 x 1520 px |
| Touchscreen | capacitive touchscreen | capacitive touchscreen |
| Screen-to-Body Ratio | 66.8% | 81.2% |
| Display area | 68.9 cm2 | 95.9 cm2 |
| Display aspect ratio | 16:9 (height:width) | 19:9 (height:width) |
| Pixel Density | 220 PPI | 271 PPI |
| Colors | 16M | 16M |
| Connectivity | vivo Y51 | Oppo A3s |
| 2G Network | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 |
| 3G Network | HSDPA 850 / 900 / 2100 | HSDPA 850 / 900 / 2100 |
| 4G Network | LTE 850 / 900 / 1800 / 2100 / 2600 - Malaysia | LTE |
| Wi-Fi | Wi-Fi 802.11 b/g/n, hotspot | Wi-Fi 802.11 b/g/n, WiFi Direct, hotspot |
| Network | GSM / HSPA / LTE | GSM / HSPA / LTE |
| SIM card | Dual SIM | Dual SIM (Nano-SIM, dual stand-by) |
| Bluetooth | 4.0, A2DP | 4.2, A2DP, LE |
| Edge | Yes | Yes |
| GPRS | Yes | Yes |
| GPS | Yes, with A-GPS, GLONASS, BDS | 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 |
| USB | microUSB 2.0 | microUSB 2.0, USB On-The-Go |
| Camera | vivo Y51 | Oppo A3s |
| Main camera | 8 MP, Single | 13 MP, Dual |
| Specs | 8 MP, AF | 13 MP, f/2.2, AF
-2 MP, f/2.4, depth sensor |
| Features | LED flash, HDR, panorama | LED flash, HDR, panorama |
| Video | 1080p@30fps | 1080p@30fps |
| Selfie camera | 5 MP, Single | 8 MP, Single |
| Multimedia | vivo Y51 | Oppo A3s |
| 3.5 mm Jack | Yes | Yes |
| Radio | FM radio | FM radio |
| Design | vivo Y51 | Oppo A3s |
| Colors | White | Red, Dark Purple |
| Dimensions | 143.8 x 71.7 x 7.5 mm | 156.2 x 75.6 x 8.2 mm |
| Weight | 157 g | 168 g |
| Battery | vivo Y51 | Oppo A3s |
| Battery capacity | 2350 mAh, Non-removable Li-Ion | 4230 mAh, Non-removable Li-Ion |
| Other | vivo Y51 | Oppo A3s |
| Release date | 2015, December | 2018, July |
| Sensors | Accelerometer, proximity, compass | Accelerometer, proximity, compass |
