Scales & sml/med/lrg starter kits

[wonkeycharm]

So i'm fairly new too Airfix model's and i'm a little confused with, whats mentioned in the title of this thread. 
so with the scale of the model, i understand that, but my confusion comes from the sml/med/lrg sets, i have 2 medium starter sets at 1:72 scale and 1 model witch is a large 1:72 scale, obviously the larger model is bigger than the two medium models, but what is the purpose of having sml, med and large sets, is it just choice or am i just being a moron and missing something here.
Kind regard Charm 

[peebeep]

I don't really know the answer, but I'll take a guess after perusing the starter sets listings. Small starter sets appear to contain a Series 1 kit and four paints, medium starter sets a Series 2 kit with six paints and large starter sets a Series 3 kit and six paints. From the same pages:

 

Airfix Starter Sets are ideal for beginners. Each Small Starter Set includes glue, brush and four acrylic paints - all that is needed to complete a fabulous first kit!

 

Large Starter Sets are perfect for gifts or to build yourself once you have mastered the basics. Each Large Starter Set includes glue, two brushes and six acrylic paints.

 

Airfix Gift Sets are ideal for more advanced modellers and include glue, acrylic paints and brushes