From the Oxford English Dictionary:

“Cover-up: an attempt to prevent people discovering the truth about a serious mistake or crime.”

“Whitewash: a deliberate attempt to conceal unpleasant or incriminationg facts about a person or organization in order to protect their reputation.”

A less authoritative source, Wikipedia, describes a cover-up in these terms:

“A cover-up is an attempt, whether successful or not, to conceal evidence of wrong-doing, error, incompetence or other embarrassing information. In a passive cover-up information is simply not provided; in an active cover-up deception is used.The expression is usually applied to people in positions of authority who abuse their power to avoid or silence criticism or to deflect guilt of wrongdoing. Those who initiate a cover up (or their allies) may be responsible for a misdeed, a breach of trust or duty or a crime.While the terms are often used interchangeably, cover-up involves withholding incriminatory evidence, while whitewash involves releasing misleading evidence.”

Wikipedia has this to say about the typology of cover-ups:

“The following list is considered to be a typology since those who engage in cover-ups tend to use many of the same methods of hiding the truth and defending themselves. This list was compiled from famous cover-ups such as Watergate Scandal, Iran-Contra Affair, My Lai Massacre, Pentagon Papers, the cover-up of corruption in New York City under Boss Tweed (William M. Tweed and Tammany Hall) in the late 1800s, and the tobacco industry coverup of the health hazards of smoking.  The methods in actual cover-ups tend to follow the general order of the list below.

Initial Response to Allegation

1. Flat Denial
2. Convince the Media to Bury the Story
3. Preemptively Distribute False Information
4. Claim That the “Problem” is Minimal
5. Claim Faulty Memory
6. Claim the Accusations are Half Truths
7. Claim the Critic Has No Proof
8. Attack the Critic’s Motive
9. Attack the Critic’s Character

Withhold or Tamper with Evidence

1. Prevent the Discovery of Evidence
2. Destroy or Alter the Evidence
3. Make Discovery of Evidence Difficult
4. Create Misleading Names of Individuals and Companies to Hide Funding
5. Lie or Commit Perjury
6. Block or Delay Investigations
7. Issue Restraining Orders
8. Claim Executive Privilege

Delayed Response to Allegation

1. Deny a Restricted Definition of Wrongdoing (e.g. torture)
2. Limited Hang Out (i.e., Confess to Minor Charges)
3. Use Biased Evidence as a Defense
4. Claim That the Critic’s Evidence is Biased.
5. Select a Biased Blue Ribbon Commission or “Independent” Inquiry

Intimidate Participants, Witnesses or Whistleblowers

1. Bribe or buy out the critic
2. Generally Intimidate the Critic By Following Him/Her, Killing Pets, etc.
3. Blackmail: Hire Private Investigators and Threaten to Reveal Past Wrongdoing (“Dirt’)
4. Death Threats of the Critic or His Family
5. Threaten the Critic with Loss of Job or Future Employment in Industry
6. Transfer the Critic to an Inferior Job or Location
7. Intimidate the Critic with Lawsuits or SLAPP suits
8. Murder; Assassination

Publicity Management

1. Bribe the Press
2. Secretly Plant Stories in the Press
3. Retaliate Against Hostile Media
4. Threaten the Press With Loss of Access
5. Attack the Motives of the Press
6. Place Defensive Advertisements
7. Buy Out the News Source.

Damage Control

1. Claim No Knowledge of Wrongdoing
2. Scapegoats: Blame an Underling for Unauthorized Action
3. Fire the Person(s) in Charge

Win Court Cases

1. Hire the Best Lawyers
2. Hire Scientists and Expert Witnesses Who Will Support Your Story
3. Delay with Legal Maneuvers
4. Influence or Control the Judges

Reward Cover-up Participants

1. Hush Money
2. Little or No Punishment
3. Pardon or Commute Sentences
4. Promote Employees as a Reward for Cover-up
5. Reemploy the Employee After Dust Clears”