As of August 3 at noon, they counted:
1,438 Palestinians killed is as follows:
1) 407 terrorist operatives:
A. 222 Hamas operatives
B. 123 PIJ operatives
C. 62 operatives from other terrorist organizations
2) 452 non-involved Palestinians
3) 589 Palestinians whose identity is not yet known
This comes out to 47% of the known casualties being terrorists, which tracks exactly to what the IDF said yesterday. Chances are these are the same figures the IDF is using, though it may be a coincidence.
At roughly the same time, the UN counted 1,717 Palestinians killed.
The difference in count of over 270 is fairly significant.
The UN doesn't publish a list of the dead (neither does ITIC) so it is not easy to identify the sources of the discrepancies. But we do have a few educated guesses.
During Cast Lead, the number of people who were reported of dying natural deaths in Gaza plummeted. It seems likely that many people who died naturally in Gaza over the past month were moved over to the "martyr" category.
There have been reports of Hamas killing collaborators. Also unverified reports of Hamas killing demonstrators. Beyond that, there are clearly people who were killed by Hamas rockets or explosions.
We have also seen quite few people double-counted, or even triple-counted, although I don't know if the UN list includes those. (The UN count is about fifty fewer than the Hamas Health Ministry count.)
Once the actual names are released, it seems very unlikely that any journalist in Gaza would endanger him- or herself to research the circumstances behind every disputed death. It also seems unlikely that the IDF figures, which have been found to be accurate (as much as could be determined) in the past, will be given the same attention as the UN or Hamas figures.