The Resonator model is available in either Concert or Tenor Size. These sizes are definined by a combination of body size and scale length (the distance from the nut to the saddle--this distance determines the spacing between the frets). The concert has a 14.72" scale length, while the tenor is 17".
When choosing your custom ukulele, you should take into consideration acoustics, comfort (how the body size feels), and playbility (primarily affected by fret spacing). There is no right or wrong answer.
You can visit our sound sample page to hear different woods in combination with different sizes of ukuleles.