Is a large coarse porcelain bowl and an enameled vat close synonyms

No. A close synonym for coarse porcelain is coarse pottery. First of all, the word porcelain means china, and coarse porcelain refers to porcelain with unenameled tires. Enamel is a product in which the surface of the iron tire is covered with an enamel layer. It is light, smooth and resistant to corrosion. Used to make daily necessities, medical utensils and corrosion-resistant equipment for the chemical industry. Sometimes also refers to the surface of the iron tire covered with enamel layer.