Ulcers and gastritis are considerably different from each other. Gastritis is a disease of the stomach in which there is an inflammation. There is inflammation because there is too much secretion of gastric juices. Ulcers, on the other hand, is a scarring of the surface of an organ or even the skin.ut the vomit’s color depends on the extent of the damage unlike in ulcers which is bloody. Both conditions are treatable with medications and antibiotics. Summary: 1.Gastritis is the inflammation of the stomach while an ulcer is the erosion of the surface of the stomach or even the gastrointestinal tract.