The difference between a credit "Freeze" and a credit "Fraud Altert"

Essentially it's this. A freeze makes it so nobody can issue you new credit without you "thawing" your credit. This can take several days.

 A fraud alert allows merchants to grant you credit, however they must go through extra steps to validate your identity. This usually includes calling you on your contact number of record.

Hope this helps,

Dan Dowling