In the Name of Allah, Most Gracious, Most Merciful.
The types of Hajj are as follows:
Tamattu`: At or before reaching the miqat, the person enters into Ihram for `Umrah only. He performs `Umrah first, then goes out of Ihram until 8 Dhul-Hijjah, when he enters into Ihram again for Hajj. This is the most common type for people from outside ofSaudiArabia.
Qiran: The person enters into Ihram for both `Umrah and Hajj, and does not go out of Ihram until the Day of Sacrifice (`Eid al-Ad-ha) at Mina. In this type of Hajj, one has to stick to the restrictions of Ihram for a longer period of time.
Ifrad: The person enters into Ihram only for the Hajj and takes it off only on the Day of Sacrifice.
In response to your question, Dr. Rif`at Fawzi, professor of Shari`ah at Cairo University , states:
In the first place, it should be noted that you have already performed the obligatory `Umrah [other scholars view `Umrah as non-obligatory], meaning that what is due on you now is only Hajj. If you do another `Umrah with this Hajj, it will be a voluntary, not an obligatory one.
As for which is the best type of Hajj (Ifrad, Tamattu` or Qiran), there is a difference of opinion among scholars in this regard. Some say that Tamattu` and Qiran are better since they require more efforts than the Ifrad, while other scholars say that Ifrad is better since the person will be free to perform Hajj with concentration.
Nevertheless, since the Prophet (peace and blessings be upon him) was in favor of the three, all of them are virtuous and the person will be given great reward of Hajj mabrur, in sha’ Allah, once he purifies his intention and dedicates it for the Sake of Allah. Keep in mind that some scholars say that the Prophet (peace and blessings be upon him) offered Ifrad Hajj, while others say that he offered Tamattu` Hajj.
Allah Almighty knows best.