Carbaminohaemoglobin is a combination of carbon dioxide and hemoglobin, CO2HHb. It is one of the forms in which carbon dioxide exists in the blood. This chemical complex is formed by carbon dioxide and hemoglobin after the release of oxygen by the hemoglobin to a tissue cell. The action is similar to that of the formation of a carbamino compound. It accounts for nearly 25% of the carbon dioxide released in the lung.
Carboxyhemoglobin, COHb Hb, is formed when inhaled carbon monoxide combines with hemoglobin in the blood. Here carbon monoxide occupies the sites on the hemoglobin molecule that normally bind with oxygen and which is not readily displaced from the molecule. Exposure to carbon monoxide thus results in cellular anoxia.
Since, both have different meanings we cannot interchange the words.