Comparison of Two Huge List SQL or .Net or Excel

http://www.splinter.com.au/reconcilingcomparing-huge-data-sets-with-c/

According to my understanding both tables are having same structure..
1. records that exist in StagingList not in Prod List  => Records only in StagingList
2. records that does not exist in stagingList but exist in Prod List.  => Records only in ProdList

you can use left join for this
for your first one 1. records that exist in StagingList not in Prod List i.e. 
To retrieve records in staginglist which are not in ProdList:
SELECT stag.* FROM [StagingList] stag LEFT JOIN [ProdList] prod
ON prod.ID = stag.ID
WHERE prod.ID IS NULL

You have to mention the Primary key columns in  On and where conditions. i.e for ex: in your table id and dte is primary column
ON prod.ID = stag.ID and prod.dte = stag.dte 
where prod.id is null or prod.dte is null

If there is no Primary column on your table, you can use except
select count(*) from [StagingList] 
except
select count(*) from [ProdList]