Both prevent blood clots from forming— blood thinners by preventing the formation of the clotting factors that hold clots together, and aspirin by preventing blood cells  from clumping into groups that become clots.
Oboje sprječavaju stvaranje krvnih ugrušaka, razrjeđivači krvi sprječavajući stvaranje činitelja zgrušavanja koji ugruške drže zajedno, a aspirin sprječavajući krvne stanice da se zgrušavaju u grupe koje postaju ugrušci.