Samsung Galaxy S8 vs vivo X21 UD

Network
2G network

GSM 850, 900, 1800, 1900

GSM 850, 900, 1800, 1900; CDMA 800 & TD-SCDMA
3G network

HSDPA 850, 900, 1700(AWS), 1900, 2100

HSDPA 850, 900, 1900, 2100
4G network

LTE frequency band 1(2100), 2(1900), 3(1800), 4(1700/2100), 5(850), 7(2600), 8(900), 17(700), 20(800), 28(700)

LTE frequency band 1(2100), 2(1900), 3(1800), 5(850), 8(900), 34(2000), 38(2600), 39(1900), 40(2300), 41(2500)
HSDPA speed

42.2 Mbps

-
HSUPA speed

5.76 Mbps

-
HSPA speed

-

HSPA
LTE speed

-

LTE
LTE-A speed

LTE-A, (4CA) Cat16, 1024 Mbps download, 150 Mbps upload

-
GPRS

Yes

Yes
EDGE

Yes

Yes

Design
Build

Corning Gorilla Glass 5 back panel

Front glass, aluminum body
SIM

Single SIM (Nano-SIM) or Dual SIM (Nano-SIM, dual stand-by)

Hybrid Dual SIM (Nano-SIM, dual stand-by)
Height

148.9 mm

154.5 mm
Width

68.1 mm

74.8 mm
Thickness

8 mm

7.4 mm
Weight

155 g

156.2 g
Payment

Samsung Pay(Visa, Mastercard)

-
Waterproof

IP68 - 1.5 m and 30 minutes

-
Dust proof

IP68

-
Colors

Arctic Silver, Coral Blue, Maple Gold, Midnight Black, Orchid Gray

Aurora White, Black, Ruby Red

Display
Display type

Super AMOLED capacitive touchscreen

Super AMOLED capacitive touchscreen
Physical size

5.8 inches

6.28 inches
Resolution

1440 x 2960 pixels

1080 x 2280 pixels
Pixel density

570 ppi

402 ppi
Display colors

16777216

16777216
Protection

Corning Gorilla Glass 5

-
Multitouch

Yes

Yes

Hardware
CPU

Octa-core

Octa-core
CPU

Quad-core 2.3 GHz

Quad-core 2.2 GHz Kryo 260
CPU(second)

quad-core 1.7 GHz

quad-core 1.8 GHz Kryo 260
Chipset

Qualcomm MSM8998 Snapdragon 835 - US / Exynos 8895 Octa - EMEA

Qualcomm SDM660 Snapdragon 660
GPU

Adreno 540 - US

Adreno 512
Memory RAM

4 GB

6 GB
Internal storage

64 GB

128 GB
Memory card

microSD

microSD(uses second SIM slot)
Memory card max

256 GB

256 GB

Main camera
Camera type

-

Dual
Main camera

12 MP, f/1.7 , 26 mm

12 MP, f/1.8 , 1/2.5" , 1.4 µm
5 MP, f/2.4
Primary camera resolution

-

4032 x 3024 pixels
Primary camera video

2160p@30fps, 1080p@60fps

1080p@30fps
Primary camera Autofocus

-

dual pixel phase detection autofocus
Primary camera flash

LED flash

LED flash
Primary camera optical image stabilization

optical image stabilization

-
Primary camera phase detection autofocus

phase detection autofocus

-
Primary camera video dual video

dual-video record

-
Primary camera video hdr

HDR

-
Camera features

1.4 µm pixel size, 1/2.5" sensor size, Auto HDR, face/smile detection, geo-tagging, panorama, simultaneous 4K video and 9MP image recording, touch focus

Geo-tagging, HDR, face detection, panorama, touch focus

Connectivity
WLAN

Wi-Fi 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac

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

Yes

Yes
WLAN WiFi Direct

Yes

Yes
WLAN WiFi Dual Band

Yes

Yes
USB

Type-C 1.0 reversible connector

microUSB 2.0
USB On-The-Go

-

Yes
Bluetooth

v5.0

v5.0
Bluetooth A2DP

Yes

Yes
bluetooth LE

Yes

Yes
Bluetooth AptX

Yes

-
NFC

Yes

-
GPS

Yes, with A-GPS

Yes, with A-GPS
GLONASS

Yes

Yes
GALILEO

Yes

-
BDS

Yes

-

Features
Messaging SMS

SMS(threaded view)

SMS(threaded view)
Messaging MMS

MMS

MMS
Messaging Email

Email

Email
Messaging IM

IM

-
Messaging Push Email

-

Push Email
Messaging Push Mail

Push Mail

-
Java

No

-
Sensors

Iris scanner, SpO2, accelerometer, barometer, compass, fingerprint (rear-mounted), gyro, heart rate, proximity

Fingerprint (under display), accelerometer, compass, proximity