Question

Difference between nematic and smectic liquid crystals

Answer 1

Nematic is a see also of smectic. Smectic is a see also of nematic.
As adjectives the difference between smectic and nematic is that smectic is (chemistry|physics) describing a class of liquid crystals whose molecules are aligned in layers, with the molecules lying perpendicular to the plane of the layers while nematic is (physics|chemistry| of certain liquid crystals) whose molecules align in loose parallel lines. 
As nouns the difference between smectic and nematic is that smectic is such a liquid crystal while nematic is a liquid crystal whose molecules align in loose parallel lines. 

Answer 2

Smectic is defined as a state of liquid crystal in which the molecules are oriented in parallel and arranged in well-defined planes. Nematic is defined as a state of liquid crystal in which the molecules are parallel but not arranged in well-defined planes.