If your cat sprays a horizontal surface, it can be differentiated from urination in that it typically leaves a long, thin wet area, rather than a puddle. Cats look very different when they are urinating merely for elimination. They use a squatting posture, usually voiding large amounts onto horizontal surfaces. Unlike cats that mark, cats that are eliminating usually scratch or dig before and after voiding. Cats rarely defecate to show marking behavior.
Cats eliminate outside the litter box for a variety of reasons.
Your cat should have a thorough physical exam by your veterinarian. If your cat is physically healthy, then the cause for the house soiling is most likely behavioral. This does not mean that your cat is being abnormal, dirty or spiteful. Emotional causes of litter box problems, while they do occur, are rare. Usually the problem is related to one of many different initiating causes.