Nope, it's a good question. "L" is for a learner judge, that's the first level. "L" judges are capable of judging schooling shows, Pony Club rallies and, lower level combined training. An "L" judge judges intro and training level tests. Then there are small "r" for recorded, who judge through Second Level and large "R" for Registered judges who judge up through Fourth Level, then an "S" level who judges up through international levels.
There are very specific criteria for each rating: competing and scoring at certain levels, judging a certain number of tests, attending judging clincs, scoring well on the written and practical exams.