Foreign trade declarations & regulations

Hi,

I am pretty confused with these terms.  Also could find that for Foreign trade declarations we can use t-code FPAWM and for Foreign trade regulations saw multiple number of programs separately for forms Z4 and Z5 like RFAWVZ5A, RFAWVZ40, RFAWVZ40N etc. 

I want to know the difference between two in terms of functionality with a real time example.  I have already gone through the documentations but no where I saw these are connected.

Also Why SAP has given multiple programs for regulations and how do I decide which one to use.

Please help.

Thanks

Vinitha