Many people use the terms Responsive Design and Adaptive Design interchangeably, but creating a distinction between them does help clarify two different approaches to the modern challenge of designing web pages that work on small and large screens.
When people first started using mobile phones to connect to websites, many of us created special versions of our sites specifically optimized to work only on small mobile devices.
As mobile devices have become “smarter,” two new approaches to designing for small and large screens have become popular — adaptive and responsive design.
Adaptive design was developed for cell phones with different features and screen sizes. It requires that the designer creates many different versions of each web page, and install complicated programming on your web server that detects each device and delivers a version of the site optimized for the specific size and features of that cell phone visitor. Adaptive design is complicated, expensive, and generally used only by large, well-financed websites.
Responsive design is comparatively a simpler approach. With responsive design, the designer creates one web page and then use multiple sets of CSS rules to change the format and layout based on the size of the browser window.
Adaptive may have been good awhile ago. But Responsive is really the only way to go because there are so many new devices being released constantly with different resolutions, it would be a waste of time to design/develop for them all in an adaptive environment… So Responsive is the way to go.