For the “Database Objects” and “Presentation Objects by Component” tabs, blue means partially granted and black means fully granted.
However for “Presentation objects by Navigator” it is different. On this tab blue means Granted Query only (which essentially means partially granted) and black means Granted (which may also mean partially granted if you look at the Details pane… it depends on whether the component parts of a screen are native to that screen or actually related to another one, in the same way that some of the items under Details pane are shown italic and some are not).
And as @RobertW mentioned I believe:
Filled in Diamond = a Procedure
Non-filled in Diamond = a Function
Nick