This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Please refer to the documentation for detailed differences.
One of the differences is , in request.getParameter("var") method, you get the parameter value of the variable "var" which was sent through the HTML page and return a String value. But in case of the request.getAttribute(Object o) method, you get the attribute added for Object o as the return value. These value are not sent through some of the component on the HTML form rather in the jsp page which produced that particular HTML page must code it like -- request.setAttribute(name, value).