Is celiac disease and gluten sensitivity the same thing? My friend has been following a gluten-free diet because she says she is sensitive to gluten. Does that mean she has celiac disease?

No. They are not the same thing. Gluten sensitivity is much less severe than celiac. They are both sort of along the same spectrum, but celiac is more severe, and gluten sensitivity is much less severe. People with celiac genes can not have celiac but be gluten sensitive.
Yes, . Yes, celiac disease is also called gluten sensitivity (or more accurately gluten sensitive enteropathy). It has also been called non-tropical sprue or celiac sprue. These terms all mean the same thing, that a person has a condition in which the immune system responds abnormally to a protein called gluten, which can cause damage to the lining of the small intestine (in medical terms called an enteropathy). The diagnosis is based on blood tests (including measurement of antibodies called tissue transglutaminase, anti-endomysial antibodies and anti-gliadin antibodies). The most accurate of these is the tissue transglutaminase antibodies. A biopsy of the small intestine taken during an upper endoscopy is also often done to confirm the diagnosis. The treatment of celiac disease is avoidance of foods that contain gluten, or a gluten-free diet. Gluten is found in wheat, rye, barley, and many prepared foods.