Mindy the most famous brand name associated with spandex is Lycra. Spandex or elastane is a synthetic fiber known for its exceptional elasticity (stretchability). It is stronger and more durable than rubber, its major non-synthetic competitor.
Chiffon is a lightweight sheer material with a slightly rough feel to it. It can be made from cotton, silk or synthetic fibers, but is usually associated with silk or nylon. Chiffon can be dyed to almost any shade desired, however if made from polyester it is difficult to dye.
Opaque is actually a material, impenetrable to visible light.
So no the materials are not similar in the least.
Oh I got this definitions off of
wikipedia.org 
Jillieann