They are two completely different, unrelated processes.
Impeachment is the process used to remove POTUS or other official from office. For POTUS, the House votes to impeach the POTUS. If it passes by majority, the POTUS is now "impeached" meaning charges are brought against POTUS. After impeachment, the POTUS goes on trial in the Senate; conviction (2/3 majority vote) means removal from office. When most people discuss the issue of "impeachment", they are talking about "impeachment (House) & conviction (Senate)".
Other than the above, the POTUS cannot be indicted on charges while in office. Nixon resigned before the House did anything and Ford issued the pardon preventing any indictments.
Censure is a public & formal reprimand or statement of disapproval. In Clinton's case it was undertaken after they failed to muster enough votes for impeachment. It's a totally separate vote and process with no direct consequence for POTUS.