Theoretically, the twins could be identical if one of the implanted eggs split after the IVF. Probably depends on what stage the embryo was in when it was implanted. That would be very rare. More than likely, the twins are fraternal. Sometimes they can tell if twins are identical by ultrasound if they share the same sac, but sometimes they each have their own sac.
My guess is two boys in the 6 lb range.