The differences between CSS2 and CSS3 are as follows:
CSS3 is divided into two various sections which are called a module. Whereas in CSS2 everything accedes into a single document with all the information in it.
CSS3 modules are supported almost on every browser and on the other hand modules of CSS and CSS2 are not supported in every browser.
In CSS3, we will find that many graphics related characteristics have been introduced like Border-radius or box-shadow, flexbox.
In CSS3, a user can precise multiple background images on a webpage by using properties like background-image, background-position, and background-repeat styles.