The University of Colorado's definition of research misconduct includes a number of categories. Research misconduct does not include honest error or differences of opinion.
Plagiarism involves portraying another person's intellectual property as one's own. The most obvious form of plagiarism is using another's words without using quotation marks and citing the source. More subtle forms may involve appropriating ideas, concepts, or data without credit and then changing the actual language so as to give the impression that the ideas are one's own, or providing a citation for one particular use, but then making extended future use of the original work without further citation.
Fabrication involves making up data, notes, or other research information and reporting them. “Data” refers to whatever forms of evidence are relevant to publication of research in a particular discipline.
Falsification involves manipulation of the research process, or altering or misrepresenting data, so that reported results are not accurate.