The difference between a modified cushion cut diamond and a brilliant cushion cut diamond?

[MP]

In my research and my time searching for the right diamond I''ve discovered that everytime I find a really good deal on a cushion it is always a modified one not a briliant. Brilliants are apparently harder to cut so they are more expensive and there are less of them around. What exacly is the difference and is the brilliant a better cut?

MP

 

[Green with Envy]

i am having touble linking--- but look at top of RT under helpful thread archives and there are two different links that explain cushions... one from boston jeff and the other called a cushion by any other name recommended by Lorelei.