One significant point of separation between both presidential scandals is that the relative cost in terms of political damage between them. Iran- Contra did not do significant damage to the Presidency of Ronald Reagan. In some ways, Regan ended up getting the proverbial "last laugh." For so long during his tenure, critics argued that Reagan was "out of touch," an indication that his age had impacted his political sense of savvy. With the disclosure of the Iran- Contra Affair, those same critics were condemning the President as "knowing too much." In an instant, the self- defeating and contradictory nature of the critique became evident for the President could not be oblivious, and yet serve as the architect for the arms for hostages nuances. Watergate, in stark contrast, helped to fit the narrative of President Nixon. It was not that far fetched to see the President as guilty of some breaches of public trust because of "Tricky Dick's" persona with the people, one in which Nixon's perception with the public was always tenuous. The impact of Watergate in bringing down a President was fundamentally more seismic than that of Iran- Contra.
On another level, I think that another primary difference between both scandals was that there was more of an ideological slant to Iran- Contra, something that the more base political manipulation that Watergate seemed to overlook. An apologist for the Iran- Contra affair can point to ideological zeal as driving the desire for the hostages to be released or to defeat the Sandinista government. The millions that were generated in profits were claimed to be funneled for anti- Marxist activity, something that drove the Conservatives in America at the time. Watergate had no such pretensions. It was an exercise in political manipulation and there could be little spin offered. For this reason, criticism for the President to resign came from both Republican and Democrat circles. Adding to this the firing of the Special Prosecutor and the President forcing a Constitutional standoff, one sees that Watergate claimed no ideological motives. It was purely power, something that Iran- Contra, according to its apologists, tried to use for an ideological end.
A fundamental similarity between both was the renewed call for increased transparency in government. A strikingly similar call for Presidential administrations to be more accountable and responsive to the public in their dealings was seen after both. The disparity between how both governments carried themselves away from the public eye and the need to ensure that the public eye is kept on government was evident in both scandals. While the cost of each is considerably less, both scandals made clear that renewed public scrutiny in the affairs of government cannot be seen as entirely bad elements.