the basic differences between HTML and HTML5:
Audio and video were not part of previous HTML version specifications, however, both are the integral part of HTML5 specifications.
Vector graphics is also an integral part of HTML5 such as SVG and canvas while vector graphics is possible in HTML with the help of various technologies such as VML, Silverlight, Flash, etc.
In HTML, browser cache can be used as temporary storage. In case of HTML5, application cache, web SQL database, and web storage is used.
HTML works smoothly with all old browsers while most of the modern web browsers have started supporting HTML5 specifications. These browsers include: Firefox, Mozilla, Chrome, Opera, Safari, etc.