>When I use this code I get 119 records:
>! AllT(myBales1.dwgrev) $ AllT(pchange.dwgrev)
>
>When I use this code I get 102 records:
>AllT(myBales1.dwgrev) <> AllT(pchange.dwgrev)
>
>Which is the correct way?

The datatype should determine which operator to use.

I prefer == and != for strings unless you are looking for a substring as Nadia pointed out.