Mostly people take adaptive and responsive as same term,but both are different
Responsive:Responsive is wider term ,it means if site is responsive if we open it in any brower or any device,it look same,we can also check its compability by minimizing and maximing the web browser,it look nice at each pixels and at each setting.For making website responsive bootstrap is used.

Adaptive:Adaptive website are those,which are set for some particular devices or at particular pixels only.Adaptive website make look different at different screen size,may you don’t find all the content or site may not look same at all devices.It may be done using different techique which is really cumbersome as we have to mannualy check at each devices,about the look of site.