Well, one difference is that swan seems to have a non-copyleft license while pdftk-java is under the copyleft GNU GPL. Given our mission, all other things being equal, Debian generally prefers a copyleft license.
- Bug#1122852: ITP: swan -- The PDF Swiss-Army CLI Uddhav
- Bug#1122852: ITP: swan -- The PDF Swiss-Army CLI Andrius Merkys
- Bug#1122852: ITP: swan -- The PDF Swiss-Army CLI Philip Hands
- Bug#1122852: swan vs pdftk-java Barak A. Pearlmutter
