Great and Small Circles - SS1 Geography Lesson Note
Great Circles
These are the largest circles that can be drawn on the Earth's surface and are formed by the intersection of the Earth and a plane that passes through its center. The Equator and all lines of longitude are great circles.
Source:(easyelimu.net)
Small Circles
These circles are formed by the intersection of the Earth and a plane that does not pass through the Earth's center. Examples include lines of latitude (except the Equator). Small circles are smaller than great circles and have varying circumferences.