Yes. Circle is just a special ellipse. The shape of an ellipse (how 'elongated' it is) is represented by its eccentricity, which for an ellipse can be any number from 0 to arbitrarily close to but less than 1. An ellipse with eccentricity equal to 0 is called circle.
So you can say that all circles are ellipses, but not all ellipses are circles.