Short answer
Crepe de Chine is a lightweight, finely crinkled silk or synthetic fabric with a smooth, matte finish and subtle drape, whereas Georgette has a distinctly rougher, pebbly texture, greater springiness, and a more sheer, bouncy drape.
Both are traded heavily across Surat's saree markets:
Tell us what you're looking for and we'll point you to the right market or supplier.