French appears in two different IB groups, and the choice is often made wrongly by students coming from francophone schools.
What French B is
It sits in the language acquisition group. The purpose is to build the language: reading, writing, listening and speaking around a set of themes.
HL goes further than SL and includes literary works; even so, the starting assumption is that the student is learning the language.
How it differs from French A
French A sits in the language and literature group and assumes the student already uses French fluently. The course does not teach the language; it teaches textual analysis.
The difference is not merely one of difficulty: the two count in different groups and contribute differently to the diploma requirement.
For a student from a francophone school
For a student educated in French for years, French B is usually too easy. A high grade is obtained and it carries little information about the student's actual level.
Universities see this. In a file where French medium education is evident, a high French B grade is an expected outcome.
The test for choosing
The question is whether the student can read a novel in French and write an analysis of it without the language itself being the obstacle.
If it is not, French A is correct. If it is, French B is correct and there is nothing to apologise for in that.
Taking two language A courses
It is possible and brings a separate certificate on the diploma. Turkish A and French A can be taken together, but that means a heavy writing load and it has to be counted against the remaining five subjects.