1) The link between dietary cholesterol and blood cholesterol.

2) The link between cholesterol and heart disease risk.

The former exists because research has shown that a large number of people don't seem to see an increase in blood cholesterol when they increase their dietary cholesterol, as I mentioned in the article.

The latter exists because people with seemingly healthy cholesterol levels, still develop heart disease, which has led to looking for alternative risk indications e.g. number of cholesterol particles vs total amount of cholesterol - the theory being that smaller, denser cholesterol particles may carry less total cholesterol but are more likely to cause plaque build up in the arteries.