Product
Vivo Z3
Vivo Z3
Xiaomi Redmi K20
Xiaomi Redmi K20
Battery
Charging - 18W wired
Type 3315 mAh, non-removable Li-Po 4000 mAh, non-removable
Body
Build - Glass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frame
Dimensions 156 x 75.6 x 8.1 mm (6.14 x 2.98 x 0.32 in) 156.7 x 74.3 x 8.8 mm (6.17 x 2.93 x 0.35 in)
SIM Nano-SIM + Nano-SIM Nano-SIM + Nano-SIM
Weight 164 g (5.78 oz) 191 g (6.74 oz)
Comms
Bluetooth 4.2, A2DP, EDR, LE, aptX 5.0, A2DP, LE, aptX HD
NFC No Yes (China only)
Positioning GPS, GLONASS, BDS GPS, GLONASS, GALILEO, BDS
Radio FM radio FM radio
USB microUSB 2.0, OTG USB Type-C 2.0, OTG
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
Display
Protection - Corning Gorilla Glass 5
Resolution 1080 x 2280 pixels, 19:9 ratio (~400 ppi density) 1080 x 2340 pixels, 19.5:9 ratio (~403 ppi density)
Size 6.3 inches, 99.1 cm2 (~84.0% screen-to-body ratio) 6.39 inches, 100.2 cm2 (~86.1% screen-to-body ratio)
Type IPS LCD Super AMOLED, HDR
Features
Sensors Infrared Face ID, fingerprint (rear-mounted), accelerometer, proximity, compass Fingerprint (under display, optical), accelerometer, gyro, proximity, compass
Launch
Announced 2018, October. Released 2018, October 2019, May. Released 2019, June
Status Discontinued Discontinued
Main Camera
Dual 16 MP, f/2.0, PDAF 2 MP, f/2.4, (depth) -
Features LED flash, HDR, panorama Dual-LED flash, HDR, panorama
Triple - 48 MP, f/1.8, 26mm (wide), 1/2.0", 0.8µm, PDAF 8 MP, f/2.4, 53mm (telephoto), 1/4.0", 1.12µm, PDAF, 2x optical zoom 13 MP, f/2.4, 12mm (ultrawide), 1/3.1", 1.12µm
Video 1080p@30fps 4K@30fps, 1080p@30/120/240fps, 1080p@960fps
Memory
Card slot microSDXC (dedicated slot) No
Internal 64GB 4GB RAM, 64GB 6GB RAM, 128GB 6GB RAM 64GB 6GB RAM, 128GB 6GB RAM, 256GB 8GB RAM
  - UFS 2.1
Misc
Colors Starry Night, Aurora Blue, Dream Powder Carbon black, Red flame, Glacier blue, Pearl White
Models V1813BT, V1813BA M1903F10I
SAR - 1.07 W/kg (head)     0.72 W/kg (body)    
Network
2G bands GSM 850 / 900 / 1800 / 1900 GSM 850 / 900 / 1800 / 1900
3G bands HSDPA 850 / 900 / 2100 HSDPA 850 / 900 / 1900 / 2100
4G bands 1, 3, 5, 8, 34, 38, 39, 40, 41 1, 3, 5, 7, 8, 34, 38, 39, 40, 41
Speed HSPA, LTE HSPA, LTE
Technology GSM / CDMA / HSPA / LTE GSM / HSPA / LTE
  CDMA 800 / 1900 & TD-SCDMA -
Platform
Chipset Qualcomm SDM670 Snapdragon 670 (10 nm)Qualcomm SDM710 Snapdragon 710 (10 nm) Qualcomm SDM730 Snapdragon 730 (8 nm)
CPU Octa-core (2x2.0 GHz 360 Gold & 6x1.7 GHz Kryo 360 Silver)Octa-core (2x2.2 GHz 360 Gold & 6x2.2 GHz Kryo 360 Silver) Octa-core (2x2.2 GHz Kryo 470 Gold & 6x1.8 GHz Kryo 470 Silver)
GPU Adreno 615Adreno 616 Adreno 618
OS Android 8.1 (Oreo) Android 9.0 (Pie), upgradable to Android 10, MIUI 12
Selfie camera
Features HDR HDR
Single 12 MP, f/2.0, (wide), 1/2.8", 1.28µm Motorized pop-up 20 MP, f/2.2, (wide), 1/3.4", 0.8µm
Video 1080p@30fps 1080p@30fps
Sound
3.5mm jack Yes Yes
Loudspeaker Yes Yes
  - 24-bit/192kHz Hi-Res audio