Zip codes and postal codes are essentially the same and serve the same purpose but for the zip code it is mainly used in the united states of America and for the postal code it is used in the UK and other countries.

History of the postal code.
The postal code which is used for mail sorting people looks as a result of increase in the complexity of postal delivery as there was an increase in the population growth in London in 1857 was divided into ten districts and Liverpool in 1864 by 1930 the idea of extending poster district even too small town was idealize which developed into postal code as we define today countries which followed the united kingdom in abducting the postal code system include the Ukraine Soviet socialist republic in December 1932 which was abandoned in 1939 the next country which adopted the postal code system was Germany in 1941 followed by Argentina and then united states(Zip code).

Brief History of the Zipcode
In the early days of the US postal mailing service, address where not regulated you might have the street address, the city and the state but you could not see a zip code. Which was much better than better than relying message delivery on family or friends. In 1961 there was an increased efficiency in implementing a nationwide improve mailing system which was much more feasible. postmaster General Edward Day took Philadelphia postal inspector Robert moon’s proposal for the improvement in the postal district code and initiated the zonal improvement plan otherwise known as the zip code.this plan expanded the two-digit city coding system into a five digit system which included a three digits for the general geographic area followed by the 2 digit district code so that when addressing a mail you would place your zip code at the end of the address after the state.

source:http://zippostalcode.com/clear-difference-postal-codes-zip-codes/

Postal codes are used worldwide to identify regions for mail delivery. ZIP codes, a term specific to the United States, stand for "Zone Improvement Plan" and serve a similar purpose. While both ensure efficient mail sorting and delivery, ZIP codes are exclusive to the U.S., reflecting its unique postal zones, whereas postal codes are used globally under various systems and names.