In my opinion, the difference is on the focus: “certificated” is related to the formal fact of being pinned with a certificate/medal/whatever, while “certified” should be related to the actual knowledge and ability to do something.

I would definitely prefer “certified” every time; “certificated” sounds ugly to me as well…

In the US, anyone who wants to fly an aircraft must get a “Pilot’s License” … but there actually is no such thing … after meeting requirements an applicant will be issued an “Airman’s Certificate”.

On that certificate, the issuing agency, the FAA, will also annotate the various “Ratings” that the airman holds. These would indicate the type and category of aircraft s/he may pilot, and whether or not s/he may pilot aircraft for profit or in scheduled airline service.

Another ‘Rating’ is one of several levels of “Flight Instructor”.

So, although the basic document is without doubt an operator’s license, that terminology is almost never used legally or formally … in ‘the business’, s/he is a “certificated airman” and if properly certified is also an instructor of other airmen. (in ordinary terms most certainly a teacher of flying skills) and is “certified by his certificate to have the right to exercise the privileges as defined on his certificate”. Simple, no?

Little wonder the majority of people employed in this specialized area of teaching simple call themselves CFI’s, and let others argue if the “C” is for “certificated” or “certified”.

Our human capacity to obfuscate never ceases to amaze me. To continue this argument much further might, indeed, lead to one becoming “certifiable”.