Product
Vivo X21 UD
Vivo X21 UD
Xiaomi Mi 8 Explorer
Xiaomi Mi 8 Explorer
Battery
Charging 18W wired 18W wired, QC4
Type Li-Ion 3200 mAh, non-removable Li-Po 3000 mAh, non-removable
Body
Build Glass front (Gorilla Glass 3), aluminum back, aluminum frame Glass front (Gorilla Glass 5), glass back, aluminum frame (7000 series)
Dimensions 154.5 x 74.8 x 7.4 mm (6.08 x 2.94 x 0.29 in) 154.9 x 74.8 x 7.6 mm (6.10 x 2.94 x 0.30 in)
SIM Nano-SIM + Nano-SIM Nano-SIM + Nano-SIM
Weight 156.2 g (5.50 oz) 177 g (6.24 oz)
Comms
Bluetooth 5.0, A2DP, LE 5.0, A2DP, LE, aptX HD
NFC No Yes
Positioning GPS, GLONASS GPS (L1+L5), GLONASS (L1), BDS (B1), GALILEO (E1+E5a), QZSS (L1+L5)
Radio FM radio No
USB microUSB 2.0, OTG USB Type-C
WLAN Wi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct Wi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct, DLNA
Display
Protection Corning Gorilla Glass 3 Corning Gorilla Glass 5
Resolution 1080 x 2280 pixels, 19:9 ratio (~402 ppi density) 1080 x 2248 pixels (~402 ppi density)
Size 6.28 inches, 98.4 cm2 (~85.2% screen-to-body ratio) 6.21 inches, 97.1 cm2 (~83.8% screen-to-body ratio)
Type Super AMOLED Super AMOLED, HDR10
Features
Sensors Fingerprint (under display, optical), accelerometer, proximity, compass Face ID, fingerprint (under display, optical), accelerometer, gyro, proximity, barometer, compass
Launch
Announced 2018, March. Released 2018, March 2018, May. Released 2018, July
Status Discontinued Discontinued
Main Camera
Dual 12 MP, f/1.8, 1/2.55", 1.4µm, dual pixel PDAF 5 MP, f/2.4, (depth) 12 MP, f/1.8, 1/2.55", 1.4µm, dual pixel PDAF, 4-axis OIS 12 MP, f/2.4, 1/3.4", 1.0µm, AF, 2x optical zoom
Features LED flash, HDR, panorama Dual-LED flash, HDR, panorama
Video 1080p@30fps 4K@60fps, 1080p@30/240fps, 720p@960fps
Memory
Card slot microSDXC (uses shared SIM slot) No
Internal 128GB 6GB RAM 128GB 8GB RAM
  eMMC 5.1 -
Misc
Colors Black, Ruby Red Black (transparent back)
Models X21UD A -
Network
2G bands GSM 850 / 900 / 1800 / 1900 GSM 850 / 900 / 1800 / 1900
3G bands HSDPA 850 / 900 / 1900 / 2100 HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100
4G bands 1, 2, 3, 5, 8, 34, 38, 39, 40, 41 1, 2, 3, 4, 5, 7, 8, 12, 17, 20, 34, 38, 39, 40, 41
Speed HSPA 42.2/5.76 Mbps, LTE (2CA) Cat6 300/50 Mbps HSPA 42.2/5.76 Mbps, LTE (4CA) Cat16 1024/150 Mbps
Technology GSM / CDMA / HSPA / LTE GSM / CDMA / HSPA / LTE
  CDMA 800 & TD-SCDMA CDMA 800 & TD-SCDMA
Platform
Chipset Qualcomm SDM660 Snapdragon 660 (14 nm) Qualcomm SDM845 Snapdragon 845 (10 nm)
CPU Octa-core (4x2.2 GHz Kryo 260 Gold & 4x1.8 GHz Kryo 260 Silver) Octa-core (4x2.8 GHz Kryo 385 Gold & 4x1.8 GHz Kryo 385 Silver)
GPU Adreno 512 Adreno 630
OS Android 8.1 (Oreo), Funtouch 4 Android 8.1 (Oreo), upgradable to Android 10, MIUI 12
Selfie camera
Single 12 MP, f/2.0, (wide), 1/2.8", 1.28µm 20 MP, f/2.0, (wide), 1/3", 0.9µm TOF 3D, (depth/biometrics sensor)
Video 1080p@30fps 1080p@30fps
Sound
3.5mm jack Yes No
Loudspeaker Yes Yes
  32-bit/192kHz Hi-Res audio -