Product
Vivo X21i
Vivo X21i
Xiaomi Mi Max 3
Xiaomi Mi Max 3
Battery
Charging 18W wired 18W wired, QC3
Type Li-Ion 3425 mAh, non-removable Li-Ion 5500 mAh, non-removable
Body
Build - Glass front, aluminum back, aluminum frame
Dimensions 154.4 x 75 x 7 mm (6.08 x 2.95 x 0.28 in) 176.2 x 87.4 x 8 mm (6.94 x 3.44 x 0.31 in)
SIM Nano-SIM + Nano-SIM Nano-SIM + Nano-SIM
Weight 159 g (5.61 oz) 221 g (7.80 oz)
Comms
Bluetooth 5.0, A2DP, LE 5.0, A2DP, LE
Infrared port - Yes
NFC No No
Positioning GPS, GLONASS GPS, GLONASS, BDS
Radio FM radio FM radio
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 - To be confirmed
Resolution 1080 x 2280 pixels, 19:9 ratio (~402 ppi density) 1080 x 2160 pixels, 18:9 ratio (~350 ppi density)
Size 6.28 inches, 98.4 cm2 (~85.0% screen-to-body ratio) 6.9 inches, 122.9 cm2 (~79.8% screen-to-body ratio)
Type Super AMOLED IPS LCD
Features
Sensors Fingerprint (rear-mounted), accelerometer, proximity, compass Fingerprint (rear-mounted), accelerometer, gyro, proximity, compass
Launch
Announced 2018, May. Released 2018, May 2018, July. 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/1.9, 1/2.55", 1.4µm, dual pixel PDAF 5 MP, f/2.2, (depth)
Features LED flash, HDR, panorama Dual-LED flash, HDR, panorama
Video 1080p@30fps 4K@30fps, 720p/1080p@30fps (gyro-EIS), 720p@120fps
Memory
Card slot microSDXC (uses shared SIM slot) microSDXC (uses shared SIM slot)
Internal 64GB 6GB RAM, 128GB 4GB RAM 64GB 4GB RAM, 128GB 6GB RAM
  eMMC 5.1 eMMC 5.1
Misc
Colors Black, Aurora White, Ruby Red, Night Purple Black, Champagne Gold, Blue
Models X21i A M1804E4A
SAR - 1.58 W/kg (head)     1.42 W/kg (body)    
Network
2G bands GSM 850 / 900 / 1800 / 1900 GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2
3G bands HSDPA 850 / 900 / 2100 HSDPA 850 / 900 / 1900 / 2100
4G bands 1, 3, 4, 5, 8, 38, 39, 40, 41 1, 3, 4, 5, 7, 8, 20, 34, 38, 39, 40, 41
Speed HSPA, LTE HSPA, LTE
Technology GSM / CDMA / HSPA / LTE GSM / CDMA / HSPA / EVDO / LTE
  CDMA 800 & TD-SCDMA CDMA2000 1xEV-DO
Our Tests
Audio quality - Noise -93.7dB / Crosstalk -94.0dB
Battery (old) - Endurance rating 115h
Camera - Photo / Video
Display - Contrast ratio: 1462 (nominal), 3.061 (sunlight)
Loudspeaker - Voice 68dB / Noise 71dB / Ring 83dB
Performance - AnTuTu: 119229 (v7) GeekBench: 4907 (v4.4) GFXBench: 6fps (ES 3.1 onscreen)
Platform
Chipset Mediatek MT6771 Helio P60 (12 nm) Qualcomm SDM636 Snapdragon 636 (14 nm)
CPU Octa-core (4x2.0 GHz Cortex-A73 & 4x2.0 GHz Cortex-A53) Octa-core (4x1.8 GHz Kryo 260 Gold & 4x1.6 GHz Kryo 260 Silver)
GPU Mali-G72 MP3 Adreno 509
OS Android 8.1 (Oreo), Funtouch 4 Android 8.1 (Oreo), upgradable to Android 10, MIUI 12
Selfie camera
Single 24 MP, f/2.0, 26mm (wide), 1/2.8", 0.9µm 8 MP, f/2.0, 1/4.0", 1.12µm
Video 1080p@30fps
Sound
3.5mm jack Yes Yes
Loudspeaker Yes Yes, with stereo speakers
  32-bit/192kHz Hi-Res audio -