what is the difference between the lunar and western calendar?

The two calendars were designed by ancient people who observed the sky and stars and moon and noticed that things repeated on a regular pattern over the years.

A western calendar is based on the fact at every 365 days, the sun is in the same position on the horizon when it rises and sets. Then it changes a little each day. So it's based on the earth's 1-year trip around the sun.

The lunar calendar is based on the fact that every 28 days, the moon goes through a cycle of phases (full moon, half mooon, new moon, etc.). Then it starts over again. So it's based on the moon's 28-day trip around the earth.

Those two cycles (earth's travel around sun and moon's travel around earth) don't match. So the 2 calendars don't start and end on the same dates.

The months are something else--they're pretty random, as to 30 or 31 days. That was more of a political or social decision.

A lunar calendar is a calendar that is based on cycles of the lunar phase. A common purely lunar calendar is the Islamic calendar or Hijri Qamari calendar.

http://www.answers.com/topic/lunar-calendar-2

A solar (or western) calendar is a calendar whose dates indicate the position of the earth on its revolution around the sun (or equivalently the apparent position of the sun moving on the celestial sphere).

more........

http://www.answers.com/topic/solar-calendar-2