I have just discovered that the prescription I was given for my spectacles is different from my contact lens prescription, is this right?
Yes. It's often necessary to have two different prescriptions for spectacles and contact lenses because of the way each works with the eye.
Because contact lenses are in contact with the eye and spectacles sit further away, the prescription may be different because of the way your eye focuses through each lens.
Contact lens specifications also include details about the shape and material of the lenses that accurately fit your eyes.