what is the difference between a parliamentary democracy and a presidential democracy?

Answer 1

Parliamentary
You elect the parliament, then they elect the Prime Minister
Presidential
You elect the parliament and the President.
In Parliamentary, Parliamament and PM are from the same party. In Presidential this may not be the case.

Answer 2

Dear Singapore resident, Please excuse the above two answers. Most people in the west can spell as well as read a question. A parliamentary democracy is where the people themselves do not make laws or appoint members of the executive but leave that to their duly voted in representatives. What is simply known as a democracy, or sometimes as a direct democracy, is where the people themselves vote on the issues. Some examples would be ancient Greece, modern day Switzerland or some New England states in the United States.

Answer 3

A Parliamentary democracy is a political system is based on the idea that Parliament is supreme. The people choose representatives at regular elections.

A presidential democracy, or a congressional system, is a system of government where the executive branch is elected separately from the legislative.

This is a good article which explains Democracy in further detail:

http://www.dadalos.org/int/Demokratie/demokratie/grundkurs1/Material/typen.htm