The treble recorder, also named alto recorder is a popular choice of instrument to learn after the descant recorder.
As it is bigger than the descant then the finger holes are wider apart and the tone is richer and deeper.
Treble Recorder Music is written at the pitch it is played ( not an octave lower like that of the descant recorder ).
The lowest note is no longer C but F ( the F above middle C on the piano ) and hence is in the key of F. The fingerings are the same as the descant recorder, but you play the scale of F ( F G A Bflat C D E F ) from the lowest note instead of the scale of C ( C D E F G A B C ) from the lowest note. This change of key can be confusing at first but with a little practise and time you will be able to play either instrument without thinking.
The treble recorder was the instrument used primarily for solos and orchestral parts in the days when recorders were popular.