The difference between server side and client side code is that server side
code is always process by server whereas client side code is executed by client
side script or to be precise client side browser.

If we want to access server side database or files we will have to use server
side code and if we want to handle client side validation we will have to use
client side code.

The common script used for client side script is JavaScript. whereas for server
side code the common script is VBScript.

Client side code validate the data before sending it to server. Where as server
side code validate data to check whether sent data is correct or not.