The DVD sets for all the series reflect the original release of that series in the U.S.

The first aired season of Star Trek: Voyager began with "Caretaker" on January 16, 1995 and ended with "Learning Curve" on May 22. That is 15 episodes (the pilot episode was two hours long, and is in two parts on the DVD).

The second season DVD box set begins with "The 37s" which first aired on August 28 of that year, the first episode of the new season. That box set has 26 episodes.

See the complete Voyager episode list here.