Explain the difference between structural proteins and functional proteins.

  Like the name suggests, structural proteins are used for structural purposes and functional proteins are used to "make things happen". 

Structural proteins are dominated by the secondary protein structure and are often fibrous. 
Example: Collagen in connective tissues, actin and myosin in muscles (these have contractile properties), etc. 

Functional proteins are dominated by the tertiary structure and are often globulars. 
Example: Enzymes are functional proteins that reduces the activation energy in order to speed up reaction (e.g. Catalase, amylase), insulin is a type of hormone which is also protein, hemoglobin are proteins that transport oxygen, antibodies and immunoglobulins (protective purposes), etc