The comparisons between President Richard Nixon, the Watergate scandal that helped end his presidency and President Trump are coming with an increasing frequency these days, particularly after Trump's firing of FBI Director James Comey Tuesday.

Watergate refers to the all-encompassing series of scandals that engulfed Nixon starting with the June 17, 1972, failed break-in at the Democratic National Committee headquarters in Washington's Watergate office complex. Five men, including four Cuban exiles affiliated with the CIA and James McCord, the security director of Nixon's 1972 re-election committee, were caught inside the DNC offices with bugging equipment and photographs.

By the time Nixon resigned and left office on Aug. 9, 1974, the scandal had become a catalog of many of Nixon's abuses of power. They included FBI wiretaps of 17 government officials and journalists, a 1970 plan to relax internal security procedures to track suspected subversives, the existence of a secret White House special investigations unit called the Plumbers, the secret bombing of Cambodia and a wide-ranging dirty tricks program run by the Nixon 1972 campaign team against potential Democratic opponents.

The final straw was the release of June 23, 1972, tape of a conversation between Nixon and his chief of staff, H.R. Haldeman, in which Nixon approved a plan to use the CIA to block the FBI's investigation of the Watergate break-in.

The Trump campaign and some of his associates are being investigated by the FBI and two congressional committees for possible involvement in the Russian-led hacking of the Democratic National Committee's email system and the transfer of those emails to the online site WikiLeaks, which posts secret government and political documents online.Nothing so far that links Trump personally to the hacking or leaks.

So, what are the similarities and differences between the Trump White House and Nixon's?