Difference between Payment and CPI module

[NICKAFM]

Hi,

 

I currently have php nuke and will integrate this with oscommerce.

My client wants to use EPDQ.

 

I am going to use the module found at -

 

http://www.oscommerce.com/community?contri...mp;category=all

 

ePDQ Payment Module

ePDQ CPI Module

 

Could someone explain to me difference between a payment module and a cpi module or are they both the same but designed by different developers?

 

Lastly what information do i need from EPDQ bank to set up the module/oscommerce?

 

Thanks

 

Nick