let me start with the two designations I personally have earned, as these are the two I have personal experience with:

CPCU stands for Chartered Property Casualty Underwriter.  This is one of the best-known professional designations in the insurance industry, and also one of the more difficult ones to obtain as it requires successfully passing ten separate proctored examinations about insurance coverage, insurance industry operations, as well as accounting and legal aspects of insurance.  This designation is offered through the American Institute for CPCU.  Additionally, the CPCU designation requires one to meet certain minimum requirements for experience in the insurance field, and to adhere to a code of ethics and meet continuing education requirements.

I think it would be fair to say that the CPCU designation is generally viewed as the "gold standard" within the insurance industry as far as professional designations go.  Some have described CPCU as being the insurance equivalent of a CPA designation.  Some folks in the insurance industry have suggested that the letters really stand for "Can't Produce, Can't Underwrite", but that usually seems to be a sour grapes complaint by people who haven't made the effort to obtain the designation.  I've known CPCU's who were brilliant, and I've known CPCU's who weren't so brilliant--but there is no denying that having the CPCU designation is a significant objective benchmark of expertise and experience about insurance.

APA stands for Associate in Premium Auditing.  This designation is well known within the insular field of premium auditing, and less well known by others.  It is administered by the Insurance Institute of America (a related organization of AICPCU).  This designation requires one to pass a total of four proctored examinations, two relating specifically to premium auditing and two others from among the ten CPCU examinations.  Within the premium auditing field, this one seems to be generally viewed as "the" professional designation for premium auditors.

Here are some other professional designations for insurance professionals that this writer does not personally hold, but has some knowledge of:

CIC stands for Certified Insurance Counselor.  This is conferred by the National Alliance for Insurance Education and Research.  This organization has its roots in the insurance agent community, and has created the CIC designation as a professional designation for insurance agent.  To attain this designation, one must attend five courses on insurance related subjects, and then successfully pass examinations on the contents of those five courses.*

*we had earlier written that passing the examinations was optional, but this was in error.  To attain the CIC designation, five examinations of the course materials must be passed by the applicant.  We regret our earlier error.