Flight ticket reservation systems - comparing two applications' complexity

We already know how to estimate the time needed to develop the application, thereupon let's consider another use of function points. How to compare two illusorily incomparable applications?

Let us imagine two flight ticket reservation systems, each of them written in a different programming language. One consists of ten thousand lines of code, and another one of two thousand. But does it mean the first system is more complex than the second? Not exactly, because the whole difference between systems - basically - refers to the language's syntax.

The same command written in one language can take five lines of code, and hundred in another, but the way it is supposed to work is the same.

Due to that, we shouldn't consider both systems not complex just because they - both - require inputting flight destination and date only. There is a lot of information that needs to be analyzed to answer each inquiry and that's exactly what should be paid attention to while comparing systems' complexity. Conclusions? Never treat number of lines of code, and end user's requirements seriously. The FPA method was invented for avoiding the misunderstanding caused by wrong presumptions.