Facebook defended its support for the Cyber Intelligence Sharing and Protection Act (CISPA), a controversial cyber security bill critics often compare to the unpopular Stop Online Piracy Act (SOPA).

In a Facebook blog post, Joel Kaplan, Facebook's Vice President-U.S. Public Policy, explained the difference between the two bills and how CISPA would protect Facebook and other websites.

Most importantly, Kaplan says Facebook or other companies would not be required to share its users data with the government or any other site under CISPA. Instead, the cyber bill allows the government to pass along cyber threat data to companies like Facebook to better protect their sites. He explained further that CISPA would not require Facebook to share more information with the government than it already shares, which does not include user's private data.

"One challenge we and other companies have had is in our ability to share information with each other about cyber attacks. When one company detects an attack, sharing information about that attack promptly with other companies can help protect those other companies and their users from being victimized by the same attack," Kaplan wrote a blog post on Friday. "Similarly, if the government learns of an intrusion or other attack, the more it can share about that attack with private companies (and the faster it can share the information), the better the protection for users and our systems."

The post was prompted after several privacy and civil liberties groups have opposed CISPA and asked Facebook to not support the bill. CISPA bill sponsor Rep. Mike Rogers (R-Mich.), chairman of the House Intelligence Committee, has said CISPA is not another version of SOPA, but that hasn't convinced the critics.

"The concern is that companies will share sensitive personal information with the government in the name of protecting cybersecurity," Kaplan wrote. "Facebook has no intention of doing this."

CISPA differs from SOPA in that it protects computer networks from being attacked by hackers, while SOPA focused on intellectual property and copyright protection, Rogers has said. SOPA bill sponsor Lamar Smith (R-Texas) withdrew the bill in January.

Kaplan doesn't want critics to worry about CISPA having any effect on Facebook users' privacy. He explains there is still time for the bill to be modified and that Congress is working with privacy and civil liberties groups to address questions and privacy concerns about CISPA.

"We hope that as Congress moves forward in considering this and any other cyber legislation, the result will be legislation that helps give companies like ours the tools we need to protect our systems and the security of our users’ information, while also providing those users confidence that adequate privacy safeguards are in place," Kaplan said.