DIFFERENCE BETWEEN WE20 AND BD64

HI

What is the difference between creating partnerprile in WE20 and BD64..

by using both transactions we can create partner profile.. but then what is the difference neween these two.. is there any restriction is there for select the particular thing..

and generating partner profile we are using BD82 .. what is this generating meansing.. why we need to do this.. plz explain briefly..

thansk

Babu