what is the different between PHP 5.1.6 and 5.2.6?

Can any one tell me what is the different between PHP 5.1.6 and 5.2.6?

I am creating a web site on my localhost using PHP 5.2.6 but my server is having the PHP version 5.1.6.
Will this having problem when upload to my server?
What should need to take note in order to prevent the error cause by different in version?

Hoping that someone could alert me on this issue.

Thanks

http://www.php.net/ChangeLog-5.php

Most scripts should run fine so long as they are on a relatively close version of PHP. Most changed between versions are bug and security fixes.

Thank you