Atmas are categorized into three. BaddAtma, MuktAtma, and NityAtma.
BaddAtma includes people like us. We are born, we live and then we die. And then we are born again in some other form in some other place. Badda means bonded or controlled. A BaddAtma is controlled by his karma and is caught in the cycle of birth and death.
Next is MuktAtma. Here Mukti means release. When a BaddAtma strives hard and attains Mukti from this birth and death cycle, he becomes a MuktAtma.
The third category NityAtma is totally different from the above two. Also called as Nityasooris, they are the permanent residents of Vaikuntham.
They live there always. They are not affected by Karmas or this mundane life. E.g Garuda, Vishwaksena, Adisesha and many more. Paramapadam or Vaikuntham is the divine abode of Sriman Narayana.
Both the MuktAtma and NityAtma are engaged in constant service to Bhagavan in Vaikuntham. The difference is that, when Bhagavan takes various avatar on earth, the Nityasooris also come down along with Him and assist Him. Upon completion, they go back to Vaikuntham along with Bhagavan. There again they will continue to enjoy doing service to Him. The Vedas say,
तद् विष्णो परमम् पदम् सदा पश्यन्ति सूर्याह
Tad Vishno paramam padam sada pasyanti sUrayaha.
Meaning: The sooris or Nityasooris are the divine souls in parama padam who are ever in service to Bhagavan and are always looking at Him.
To mention a few names of Nityasooris, Garuda we all know is the vAhana or vehicle of Bhagavan, Vishwaksena is supposed to be the commander-in- chief of His army. Adisesha is the 1000 headed snake on which Bhagavan lies down. From our Puranas, we see that in treta yuga when Bhagavan took Rama avatar, Adisesha was born as His younger brother Lakshmana. In Dwapara yuga he was born as Balarama the elder brother of Krishna.
In short, Bhagavan and Nityasooris are inseparable. They are never born like how the Badda and Mukta atmas are born. They live forever in the divine abode of Sriman Narayana.