Receiving actual college credit is considered more rigorous than receiving a certificate, but you can still put the class on your application. Taking the class for a certificate generally would be considered more along the lines of an extracurricular activity, whereas taking it for college credits would be part of your academic record and you would submit that college transcript (along with that of your high school) to colleges to which you apply.
Honors usually designates a higher level class OR an award won. I am not sure of the context you are asking about. “Honors” can refer to either of those. The certificate you earned could be considered an award.
Did you get professional certification after the class or was the certificate just one of completion? The former would likely be more impressive than the later, but you didn’t mention specifics, and there might be exceptions.