Answer:
From highest to lowest pitch: Soprano, Alto, Tenor, and Baritone.
The Soprano and Tenor are keyed in Bb
The Alto and Baritone instruments are keyed in Eb.
The baritone saxophone requires more lung capacity and is probably too large for a younger student.
The soprano saxophone is the most difficult of these four to play in tune.
Therefore most students of the saxophone begin on Alto or Tenor try others after they have some proficiency.