French furniture is a little easier to follow than some other styles. There are, of course transitional styles, but the three famous and popular Louis styles are simple to identify. As you proceed into the 19th century there are a host of other styles, some of which relate pretty closely to Italian and English furniture.
Louis XIV The Sun King...Sun motifs. Big, heavy and heavily carved. Lots of gold and bronze on monumental and expensive pieces. Bulbous turnings. Heavy patterned fabrics and tapestries if original fabrics are present. Dark rich colors. Sometimes over-ornamented. Sinuous snake-like chair arms. I think of Jacobean as a near relative of Louis XIV in England.
Louis XV More delicate, soft elegant curves, fewer stretchers on legs of chairs and tables. Generous size seats like for large skirts. Look lower to the ground though not really much different in actual measurement. Little scrolls and delicate carvings. Legs terminate at the ground in scrolls and little pad feet. Scrolled feet might look like they are balanced on top of corks. Original fabrics will be elegant silks and simple tapestries, sprigs and petit points. Bronze mounts are quite delicate.
Louis XVI Some of the lightness and elegance of Louis XV, but tending toward straight legs, turnings are elegant but there are few of the soft curves seen earlier. Flutes and trumpet carvings on legs etc., but restrained not at all like Louis XIV. Simple fabrics, silks stripes wreaths. A bit more vertical looking because of the straight lines from floor to seats, backs and table tops, even though the proportions have not changed much from Louis XV. Fewer wide, generous seats.