Can you please tell me how infarction and gangrene differ?

Block vs Infection: Infarction is essentially blockage of the blood supply (typically an artery) will cause tissue death. Gangrene usually refers to an infection that occurs in dead tissue. Therefore tissue infarction may reukt in gangrene when it becomes infected. In some instances gangrene may produce vascular occlusion of the micro vasculature which leads to tissue death and infarction.

Gangrene ?: Infarction refers to the early state of a tissue in which blood supply has been 'shut off' - like immediately after a heart attack (myocardial infarction). Infarcted tissue can heal if blood flow is restored. Gangrene refers to the long term state of tissue that has been completely deprived of blood supply - essentially rotting tissue. There are 'dry' and 'wet' types of gangrene.