Passive transport is defined as the movement of ions across a cell membrane from a high concentration area to a low concentration area - without the use of energy.
Passive transport is achieved by diffusion - random motions resulting in the movement of a substance from a high concentration area to a low concentration area.
Osmosis - on the other hand - applies the same concept to water, across a semi-permeable membrane.
A hypertonic solution is when the solution has a higher concentration ( hyper = more than )
A hypotonic solution is when the solution has a lower concentration ( hypo = less than )
An isotonic solution is when the concentrations on both sides are equal - resulting in no net movement.
Facilitated diffusion follows the same idea except that it is aided by a membrane protein as many important molecules required by cells cannot easily pass through the plasma membrane.