Guitar Maker is quite specific, Luthier is more general, but often used wrongly.
I have been waging a one man war against "Luthier" for a long time now, here is the history.
The word "Luthier" is French, "one who makes Lutes", but is used throughout Europe to describe a maker or repairer of any stringed instrument, including violins, harps etc. Around 1975, it started being used in America by individual guitar makers to differentiate themselves from those who had built up larger companies. So far, so good.
The word has now been adopted as if it were a qualification, sometimes with "master" added to it, although no exams, training or experience is involved. In most cases, I think it is "disingenuous", an attempt to sound superior, and to cover up amateurism and lack of knowledge.
To me its a bit like saying "campanologist" rather than "bell ringer", pretentious and unnecessary, but I know I’m fighting a losing battle. Even the larger companies and experienced makers now call themselves Luthiers, and "Luthier built" is a vague attempt at saying something else, but no-one knows what it is.
I won't give up easily, but I can foresee the day when I use the L word myself. One last comment - I’ve been stopped for speeding in the UK and the USA, each time by a policeman, never a gendarme