Major differences between 7.1.1 and 7.4.x

Hi ,
can any one tell me the major difference between 7.1.1 and 7.4.x version
of postgresql,
also please tell me what are things to considered when upgrading
postgresql from 7.1.1 to 7.4.x.

Please reply me..

Thanks & Regards
J Mageshwaran

********** DISCLAIMER **********
Information contained and transmitted by this E-MAIL is proprietary to
Sify Limited and is intended for use only by the individual or entity to
which it is addressed, and may contain information that is privileged,
confidential or exempt from disclosure under applicable law. If this is a
forwarded message, the content of this E-MAIL may not have been sent with
the authority of the Company. If you are not the intended recipient, an
agent of the intended recipient or a person responsible for delivering the
information to the named recipient, you are notified that any use,
distribution, transmission, printing, copying or dissemination of this
information in any way or in any manner is strictly prohibited. If you have
received this communication in error, please delete this mail & notify us
immediately at admin(at)sifycorp(dot)com

Complete Coverage of the ICC World Cup '07! Log on to www.sify.com/khel for
latest updates, expert columns, schedule, desktop scorecard, photo galleries
and more!

Watch the hottest videos from Bollywood, Fashion, News and more only on
www.sifymax.com

For the Expert view of the ICC World Cup log on to www.sify.com/khel.
Read exclusive interviews with Sachin, Ganguly, Yuvraj, Sreesanth, Expert
Columns by Gavaskar, Web chat with Dhoni and more! .