A pharming scheme differs from phishing because:

A pharming scheme is distinct from phishing in that it eliminates reliance on users actively clicking a link to be redirected to a fraudulent site. In a pharming attack, the attacker can manipulate the victim's DNS settings or exploit vulnerabilities so that when the user enters a legitimate web address, they are automatically redirected to a malicious site without their knowledge. This means that even if a user is cautious and avoids suspicious emails or links, they can still be compromised if their system has been affected by pharming.

Phishing, on the other hand, typically requires an attacker to entice victims to click on a link that leads to a fraudulent site designed to capture personal information. Therefore, the ability of pharming to operate without this user interaction makes it a particularly insidious form of cybercrime, as it can affect any user navigating to a legitimate site that has been compromised.

Overall, the fundamental difference lies in the method of attack: pharming does not depend on user behavior for the initial compromise, thereby allowing it to circumvent many of the precautions that users may take against phishing attacks.