Java is pure object oriented programming language from Sun. While Javascript is a object based scripting language from Netscape.

Javascript is designed to use within a web page. It is embedded in a html to create special effects of web pages or for validations. You can use JavaScript for even dynamic up gradation of the website.

Javascript is interpreted or compiled at client side, but Java compiled on server before execution on client. So the validations written with JavaScript and checks the validation at client side. In some browsers we can also disable the JavaScript. In such cases we can\\\'t check the validations. You can also witness where Server side checking takes place,  which is written in Java.

Javascript allows loose data type declaration. That is why we need not define which type of variable it is. Simply we can define it as var. But, Java has strong typing where in the declaration  had to define what type of variable.  The Java files extension is termed as .Java where as the Javascript files extension are .js.