The terms 'author' and 'inventor' are not synonymous.
Co-authors may not necessarily be co-inventors.
Generally, an author should be the individual(s) who wrote or contributed to writing a particular work.
In the scientific world, authors of journal articles are typically those persons involved in designing or performing the experiments or in writing the resulting manuscripts. In addition, authorship is sometimes granted for the recognition of hard work or even for financial support.
In contrast, inventors of subject matter in patents have to be legally determined, according to the criteria of patent law, by their involvement in the original conception of the invention (not necessarily the same individual(s) involved in determining whether the invention works, or writing the analysis).