Some people seem to define Positive Criticism as all positive comments without regard to the writer's intent. If the content contains negative comments, it is immediately classified as Negative Criticism.
Criticism, by definition is negative comments:
1. the expression of disapproval of someone or something based on perceived faults or mistakes.
synonyms: censure, condemnation, denunciation, disapproval, disparagement, opprobrium, fault-finding, attack, broadside, stricture, recrimination
2. the analysis and judgment of the merits and faults of a literary or artistic work.
"alternative methods of criticism supported by well-developed literary theories"
synonyms: evaluation, assessment, appraisal, analysis, judgment
I agree with your interpretations of positive (aka constructive) and negative criticism in that it all depends on how it is presented.
All positive comments are not criticism, but just stroking the writer's ego. It's like giving an award just for showing up. It does not attempt to encourage the writer to improve and implies that substandard work is better than it actually is.
As for how I classify the feedback I receive, it depends on how it is presented.
In my story 'The Loser', I have females playing baseball in school instead of softball. I had comments and criticisms that were positive and asked if I actually intended to say softball, since that is what girls in our schools play. The other just basically said "Hey stupid, girls only play softball in school. Fix it." I replied that in MY universe, everybody plays baseball.
Another bit of feedback I received concerned the choice of weapons I had made. The comment indicated that I had made a poor choice in weapons and recommended a variety of others that would be better suited for the job. I studied the recommendations, then went back and re-wrote the scene based on the new information. Had the person just written that my choices were 'f#'ed up', it would not have given me the information I needed to make a more informed selection and improve the story.