Found the brochures ...
and here are some of the key differences:
Elegance line had blue glass.
Avantgarde line had green glass.
Elegance line had halogen lamps.
Avantgarde line had xenon lamps.
Elegance line had 10 hole alloy wheels.
Avantgarde line hade 5 hole alloy wheels.
Elegance line had burl walnut wood trim.
Avantgarde line had bird's-eye maple trim.
Seat belts of Elegance line were of same color as interior trim.
Seat belts of Avantgarde line were black.
Elegance line had bumpers and rub strips of a contrasting color to body.
Avantgarde line had bumpers and rub strips of body color.
Avantgarde line had a lowered suspension compared to that of the Elegance line.
Steering wheel in Elegance line was color-code to interior.
Steering wheel in Avantgarde line was black.
There were two exterior colors unique to the Avantgarde line - metallic Amazon green and metallic Violane (looks purple in brochure).
Standard equipment was same for both lines as were available engine options.
Hope, this helps.