if product is a clent based one then there is difference between this both but if the product is webbased then no difference in my view product is build by company and kept for sale as to be sold by customers who needs them and product will be customised as per required changes(if needed) and sold to customer.in sense ur question is some what confusing as it should product testing Vs project testing otherwise webtesting Vs client server testing

NO doubt there is not difference between application and product. application is only according to client requirement and after development. where as products are first developed and then sold to clients as per their changes. producst may be web-based or windows application. usually produts are client server application which will be used within an organisation

product testing:Product testing is the branch of engineering concerned with the experimental developmental and performance characteristics of product .

In other words It is develop by the organzation and marketing by the company IT selfs

web -based application:An application in which all or part of it is downloaded

from the Web each time it is run. The term typically refers to the use of Web

browsers and Java applets. Web pages increasingly resemble the interactive

behavior of local applications. Retrieving a Web page may cause the

execution of code in the Web server as well as code in the HTML page brought

into the user's machine. Clicking an icon on a Web page may cause a Java

applet to be downloaded and executed in the user's machine.

sudhakar kolla

If you are having any doubt can ask me.