Completely different process for the two sorts of offering.
In a Reg CF offering, the Form C is filed with the SEC and the moment it shows up on the EDGAR system, the issuer can start accepting investment commitments on the intermediary's site. The SEC does not review or sign off in any way. That doesn't mean they (and other regulators) aren't looking, though!
In a Reg A offering, the SEC must review and "qualify" the offering before it goes live. (We don't use the term "approve"; the SEC never approves or blesses offerings.) If it's a Tier 1 Reg A offering, the states that the offer will be made into also have to sign off.
In both cases, you can "test the waters" before filing or qualification, but any materials you use to test the waters need to be filed with the SEC.