They're basically identical. Same drivetrain combinations offered in each. Same frame, body, etc.. The only difference might be the brakes. Late '78 had same front brakes as '79. See your other post regarding this. Give more specifics about the Jeeps you are comparing. Do they have the same drivetrain? What condition are the body and frame of each? Be specific when asking questions like this.

'75 CJ5,258 w/Howell EFI,T18a,4.27's,33's,On-board air,Warn 8274