How can I make the difference in this kind of sentence :
"French Quality Clothes"
Does it mean :
- Clothes of the well-known "french quality"
- Quality clothes from France
And How can I express the 2 without been misunderstood?
By placing the adjective before the appropriate word.
I think the best way to express the difference between the two ideas is to do exactly what you've done -- elaborate.
I'm not exactly sure what you mean by "the well-known French quality" -- I assume you are referring to certain quintessential French designs, patterns and other characteristics (I am no fashion expert). If that is the meaning, then it should be understood if you say something on the lines of
Note: I believe some authors would put quotes around the French (a distinct "French" quality) to invite the reader to apply their best interpretation of what the adjective stands for.
If the meaning is indeed as I described above, then I think this construction should be clear enough.
As for "quality clothes from France", you should definitely elaborate it as described. The use of two consecutive adjectives in front of the noun introduces a great deal of ambiguity, in my opinion. I would actually be more likely to understand "French quality clothes" as the first interpretation above, although I'd still be confused.