A credit freeze restricts access to the file
A security freeze makes it harder for someone to open new credit in your name. You generally place and lift a freeze separately with each nationwide credit reporting company.
A fraud alert tells businesses to verify identity
A fraud alert asks businesses to take steps to confirm identity before opening new credit. Contacting one nationwide bureau to place an alert generally requires it to notify the others.
Choose based on your situation
A freeze is stronger protection against new-account access, while an alert can be useful when fraud is suspected or information was exposed. Neither corrects existing report errors; use the appropriate dispute or identity-theft process for those.
Official sources
Review the current government sources before acting because requirements and contact information can change.
FTC: Credit freezes and fraud alerts IdentityTheft.gov