vivo U20 vs vivo X51 5G

Network
2G network

GSM 850, 900, 1800, 1900

GSM 850, 900, 1800, 1900; CDMA 800
3G network

HSDPA 850, 900, 2100

HSDPA 850, 900, 1700(AWS), 1900, 2100
4G network

LTE frequency band 1(2100), 3(1800), 5(850), 8(900), 38(2600), 40(2300), 41(2500)

LTE frequency band 1, 2, 3, 4, 5, 7, 8, 12, 17, 18, 19, 20, 26, 28, 32, 38, 39, 40, 41, 66
5G network

-

5G band 1, 3, 7, 8, 28, 38, 41, 77, 78 SA/NSA
HSDPA speed

42.2 Mbps

42.2 Mbps
HSUPA speed

5.76 Mbps

5.76 Mbps
LTE speed

LTE, Cat12, 603 Mbps download, 102 Mbps upload

LTE-A
GPRS

Yes

Yes
EDGE

Yes

Yes

Hardware
CPU

Octa-core

Octa-core
CPU

Dual-core 2.0 GHz Kryo 460 Gold

Single-core 2.4 GHz Kryo 475 Prime
CPU(second)

Hexa-core 1.7 GHz Kryo 460 Silver

Single-core 2.2 GHz Kryo 475 Gold
CPU(third)

Hexa-core 1.8 GHz Kryo 475 Silver
Chipset

Qualcomm SDM675 Snapdragon 675

Qualcomm SM7250 Snapdragon 765G
GPU

Adreno 612

Adreno 620
Memory RAM

4, 6 GB

8 GB
Internal storage

64 GB

256 GB
Memory card

microSD, microSDHC, microSDXC

No
Memory card max

256 GB

-
Storage

-

UFS 2.1

Main camera
Camera type

Triple

Quad
Main camera

16 MP, f/1.8

48 MP, f/1.6 , (wide) , 1/1.2" , 0.8 µm
8 MP, f/2.2 , 13 mm

8 MP, f/3.4 , 135 mm, (periscope telephoto) , 1/4.0" , 5x optical zoom
2 MP, f/2.4

13 MP, f/2.5 , (portrait) , 50 mm, 1/2.8" , 0.8 µm, 2x optical zoom
(ultrawide) , 8 MP, f/2.2 , 120˚ , 16 mm, 1/4.0" , 1.12 µm
Primary camera resolution

4608 x 3456 pixels

8000 x 6000 pixels
Primary camera video

2160p@30fps, 1080p@30fps

4K@30fps, 1080p@30fps, gyro-EIS
Primary camera flash

LED flash

dual-LED dual-tone flash
Camera features

Autofocus, geotagging, panorama, HDR, touch focus, face detection, white balance settings, ISO settings, exposure compensation, self-timer, scene-mode

Autofocus, continuous shooting, digital zoom, digital image stabilization, optical image stabilization, geotagging, panorama, HDR, touch focus, face detection, white balance settings, ISO settings, exposure compensation, self-timer, scene-mode, macro-mode, phase detection autofocus
DxOMark photo

-

117
DxOMark zoom

-

67
DxOMark video

-

102
DxOMark camera score

-

114

Selfie camera
Selfie camera type

-

Single
Selfie camera

16 MP, f/2.0 , 26 mm, 1/3.1" , 1.0 µm

32 MP, f/2.5 , 26 mm, 1/2.8" , 0.8 µm, (wide)
Selfie camera resolution

4608 x 3456 pixels

6528 x 4896 pixels
Selfie camera features

-

Face unlock
Selfie camera video

1080p@30fps

1080p@30fps
DxOMark photo

-

82
DxOMark video

-

78
DxOMark camera score

-

81

Connectivity
WLAN

Wi-Fi 802.11a, 802.11b, 802.11g, 802.11n, 802.11n 5GHz

Wi-Fi 802.11a, 802.11b, 802.11g, 802.11n, 802.11n 5Ghz, 802.11ac
WLAN WiFi Hotspot

Yes

Yes
WLAN WiFi Direct

Yes

Yes
Wi-Fi display

Yes

-
WLAN WiFi Dual Band

Yes

Yes
USB

microUSB 2.0

Type-C 2.0
USB On-The-Go

Yes

Yes
Bluetooth

v5.0

v5.1
Bluetooth A2DP

Yes

Yes
bluetooth LE

Yes

Yes
Bluetooth AptX

-

aptX HD
NFC

-

Yes
GPS

Yes, with A-GPS

Yes, with A-GPS
GLONASS

Yes

Yes
GALILEO

Yes

Yes
Beidou

Yes

-
BDS

-

Yes

Features
Sensors

Accelerometer, compass, fingerprint, gyroscope, light, proximity

Accelerometer, color spectrum, compass, fingerprint, gyroscope, proximity