Shanghai is on the same line of latitude as Cairo, Texas and San Diego. Why does it have completely different Climate ?

Many things affect local climate zones around the planet, ocean currents, mountain ranges. Western Europe is warmer than it should be due to ocean currents. London is far warmer than similar regions in Russia. The Himalayas show the effect mountains can have, as do the Andes in South America. Whether an ocean current is warm or cold can also have a strong effect on local climate and rainfall and rainfall is the difference between a place being tropical or desert.

It's the wind and the water.

San Diego and Texas have very different climates.  Texas is more prone to get tropical air and we in Southern California tend to get the air off the Pacific and it is much milder and less humid than most of Texas, particularly where most Texans live.  The prevailing winds in San Diego are onshore, meaning the wind comes mostly from the ocean.  I believe the prevailing winds in Shanghai are the same direction (easterly) but they are offshore.  This means that much of their weather is more variable.  Shanghai is much more humid than San Diego but maybe more like Houston.  Presumably the air in Cairo is mostly from the Sahara Desert and it is dry and hot.  Most of the more moist air flows to the north.  I'm no expert but that is what I think I remember reading.  When Shanghai gets its air from the Northwest in the winter, it can experience freezing.  Northwest of Shanghai is Siberia, one of the coldest places on earth. 

Because it's near an ocean with no mountains behind it.  Seattle and Halifax are another example of this.  There at approximately the same latitude, but Halifax gets MUCH colder than Seattle, because the Pacific Ocean is not only larger than the Atlantic, but deeper, and acts as a sort of "heat battery" (it gives up all the heat it's stored over summer, so Seattle stays warmer in the summer).

I suggest for a FULL discussion, you should take a meteorology class, as I am not going to "teach you the long story out of the goodness of my heart" for free.