What is the difference between Bootstrap 3 and Bootstrap 4

Bootstrap is open-source framework for create website and applications. Bootstrap is the most popular HTML, CSS and JS framework for devloping responsive websites. 

Bootstrap 4 is the latest version of Bootstrap . More changes in Bootstrap 4 comparison of Bootstrap 3.

Main Diffrences in Bootstrap 3 and Bootstrap 4 :

Bootstrap 3 Source CSS Files is LESS.
Bootstrap 4 Source CSS files Converted in SCSS.

Bootstrap 3 has 4 grid system (col-xs-3, col-sm-3, col-md-3, col-lg-3).
Bootstrap 4 has 5 grid system (.col-, .col-sm-3, .col-md-3, .col-lg-3, .col-xl-3). Bootstrap 4 has removed the xs from the lowest break point. Therefore, (col-) covers all devices.

Bootstrap 3 Offset class is like this (col-md-offset-4).
Bootstrap 4 has changed the offset class (offset-md-4).

In Bootstrap 3 we are used this (.img-responsive) class for responsive image.
Bootstrap 4 has changes the class for responsive image (.img-fluid).

In Bootstrap 3 we are used (.input-lg) and (.input-sm) to increase and decrease the input size.
Bootstrap 4 has changed to (.form-control-lg) and (.form-control-sm) to increase and decrease the input size.

Bootstrap 4 has add, remove and rename the classes.

I hope this blog has been helpful to all.

Thanks