Compare two tables

so i'm trying to figure out the best way to do this, basically, i have two data sets.

table A has:
FirstName
LastName
Address
City
State
Zip

table B has:
FirstName
LastName
Address
City
State
Zip
and a bunch of other fields (like 50 of them) that contain different bits and pieces of the person.

i KNOW table A, came out of table B, but i need to figure out exactly (within reason) what "selects" were used to create table A from table B.

is this a task for SSAS, i'm just a t-sql guy, i'm not really an SSAS guy, so i'm not even sure where to start. any ideas?