I think they start as a single letter and the more letters you had depends on the options as 1fastkia said, but also dependant on the letters I think they define whether you go for a sporty upgrade or a more luxurious upgrade
eg
L for example is the base model
LX has a few more options
SLX has the above options + some sporty options such as a spoiler and a sporty interior
GLX has the LX options, but also has say a leather interior and some classy alloys
but then again maybe I'm wrong - I'm sure I'll be corrected if I am
eg
L for example is the base model
LX has a few more options
SLX has the above options + some sporty options such as a spoiler and a sporty interior
GLX has the LX options, but also has say a leather interior and some classy alloys
but then again maybe I'm wrong - I'm sure I'll be corrected if I am