Can you please explain why celiac disease is considered dangerous, and gluten intolerance not dangerous?

Probably same: Celiac disease is also called gluten sensitive enterophy or gluten intolerance. One would need to further clarify the meaning of "gluten intolerance" to make sure this is not being misinterpretted.

Can be diiferent: Celiac disease is one type of gluten intolerance (it is actually a food-induced auto-immunity condition) that is confused with wheat allergy and usually manifests as malabsorptive diarrhea and can also include a rash and/or arthralgias. There are other types of gluten intolerance(s) that can manifest in various ways, including memory loss, balance and various other symptoms.

Immune system defect: With CD your immune system malfunctions, creating antibodies to gluten as if it were a germ but they also attack your tissues. The gut tissue is the most common to be injured,but others may have some effect. Damaged gut produces symptoms including diarrhea, dietary deficiencies, weight loss, potential for cancer, etc.? Gluten intolerance means you don't tolerate it but eating it doesn't damage you