Thats good to know, But why do they look so different? 
just two different designs , the original ones the rubber sits inside a metal sleve which needs the old one burning and the race cutting out and the new one pressing in .
the poly powerflex one just burn out the old one , cut the metal sleve out , and grease up just slide the rubber in , and tap the metal sleve in the middle to open the bush out and your fitted , million times quicker .....