difference between selenium 3 and 4 code example

Example: selenium 3 difference

Selenium-3 differences

Understand the below things to know
how Selenium-3 is different from Selenium 2:

Minimum Java version required is above 1.8
GeckoDriver is required for the latest versions of Firefox Browser
Selenium 3 open the browsers by default
in maximized mode. Hence no need to
write driver.manage().window().maximize() command
Selenium 3 is more powerful and robust than Selenium 2
Stability fixes were done on Selenium 
Grid of Selenium 3 to make it stable
Re-enabled log gathering for the 
Selenium Standalone Server
In Selenium 3, mobile automation 
support got removed i.e. AndroidDriver
and iPhoneDriver are removed from Selenium WebDriver library
We have to use other tools like 
Appium for Mobile Automation
Appium tool extends the WebDriver 
framework to create mobile tests)
Bug fixes were made for Selenium
WebDriver too in Selenium 3