Difference between Oval and Ellipse

Date: 10/18/2001 at 17:48:01
From: Tarab Ali
Subject: Geometry

What is the difference between an oval and an ellipse? Do they both 
imply the same concept, or different?

Am I right if I say that "all ellipses are ovals but all ovals cannot 
be ellipses"?

Date: 10/19/2001 at 17:36:10
From: Doctor Sarah
Subject: Re: Geometry

Hi Tarab - thanks for writing to Dr. Math.

From The Ellipses Calculator - Centre for Innovation in Mathematics 
Teaching, University of Exeter:

   http://www.ex.ac.uk/cimt/res2/calcs/callipse.htm   

    ... once the size of an ellipse has been fixed then its exact 
    shape is mathematically determined. In other words, the line 
    forming the perimeter can be drawn in only ONE way. This is 
    distinct from an oval where the perimeter has only to be a 
    concave curve, and there are many possibilities. Simply, an 
    ellipse IS an oval, but an oval may or may not be an ellipse.

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/