Adaptive and Responsive web design - What is the difference?

For the past couple of months, while I was talking to different people about mobile testing, they kept using the term "Adaptive web design" and "Responsive web design" interchangeably. Initially, I thought they were the same but became more and more curious about the terms when a colleague of mine indicated that there are some differences.I did some research and found that, they are technically NOT the same (my colleague was right :-)). I realized that people do not know the actual difference between the two and are using it interchangeably.

So, what is the actual difference between the two you may ask? Here it is-

Responsive web design - In this, you make the page responsive to the width of a browser window. So, as and when you keep resizing the browser you will see the page changing dynamically and giving the user the optimum page view in different "Browser" widths.Most of the stuff is done on the client side thus leading to some performance constraints

Adaptive web design - In this, you give the user different versions of the page based on the device being used. There is a device detection script which runs on a web server and each time a user access the website using a device, the script detects the type of device the user is using and loads up the page accordingly. It DOES NOT have anything to do with the browser width and it is related to the device screen size.Since most of the stuff is done on the server side, there is less problems due to page performance.

Although, the above 2 approaches have different types of implementations they are similar in terms of its goal  i.e giving the optimum experience to the user in terms of the page being displayed when accessed via a phone, tablet, phablet or a desktop browser.

I used the below links to get a better idea about the similarities and differences

http://www.techrepublic.com/blog/web-designer/what-is-the-difference-between-responsive-vs-adaptive-web-design/

http://www.searchenginepeople.com/blog/the-difference-between-adaptive-design-and-responsive-design.html

http://www.digitalfamily.com/tutorials/css-article/whats-the-difference-between-adaptive-and-responsive-web-design/

So there you go. Finally I found the answer to my question and hopefully this gives some clarity to people who have the same doubts about the 2 designs in their mind.

Next time, you see a person using these terms interchangeably, what would you say? :-)