Molecules move in and out freely from high to low concentration

Active Transport - requires chemical energy because the process of transport is the movement of biochemicals from areas of lower concentration to higher concentration.

Passive Transport - does not require energy because the process of transport is the movement of biochemicals from areas of higher concentration to lower concentration. 

Types of transport:
Active Transport - endocytosis, cell membrane/sodium-potassium pump and exoctyosis

Passive Transport - diffusion, facilitated diffusion, and osmosis.

Types of particles transported:
Active Transport - proteins, ions, large cells, complex sugars

Passive Transport - anything soluble in lipids, small monosaccharides, water, oxygen, carbon dioxide, sex hormone, etc.