As nouns the difference between hemoglobin and carboxyhemoglobin

is that hemoglobin is the iron-containing substance in red blood cells that transports oxygen from the lungs to the rest of the body; it consists of a protein (globulin), and haem (a porphyrin ring with an atom of iron at its centre) while carboxyhemoglobin is the stable complex of carbon monoxide with hemoglobin; it prevents the normal complexing with oxygen and thus leads to anoxia.