Responsive web design is a web design that provides an optimal view of the website and a good interaction experience (like reading, navigation) in all the devices (mobile, tablets,computer monitors). So it's the "same" design but it adapts to the device where you see the web.
Check this link to know more: https://en.wikipedia.org/wiki/Responsive_web_design
Responsive design is all about a website design which interacts with the user, no matter if we take into the terms on bots or instruction content and all. The design is simple yet attractive to engage the user and lets the user spend more time surfing the website.