SHA1: differences between CI library and hash/mhash (from PHP)?

[eluser]Optimus Prime[/eluser]
Hi, my question is what are the differences between SHA1 encryption generation from CI library (for the security helper) and hash/mhash from PHP (using "MHASH_SHA1" as a parameter)?

For PHP and encryption newbies:
About hash/mhash, it can be found php manual:
Hash function (PHP)
mhasf function (PHP)

[eluser]deviant[/eluser]
The SHA1 function in CI uses PHP's sha1 function anyway, it just puts in checks to see if the function is actually available, and if it isn't it uses CI's SHA1 library.