Dhruva Mahārāja realized that the Supreme Absolute Truth, the Personality of Godhead, acts through His different energies, not that He becomes void or impersonal and thus becomes all-pervading. The Māyāvādī philosopher thinks that the Absolute Truth, being spread throughout the cosmic manifestation, has no personal form. But here Dhruva Mahārāja, upon realization of the Vedic conclusion, says, "You are spread all over the cosmic manifestation by Your energy." This energy is basically spiritual, but because it acts in the material world temporarily, it is called māyā, or illusory energy. In other words, for everyone but the devotees the Lord's energy acts as external energy. Dhruva Mahārāja could understand this fact very nicely, and he could understand also that the energy and the energetic are one and the same. The energy cannot be separated from the energetic.
The identity of the Supreme Personality of Godhead in the feature of Paramātmā, or Supersoul, is admitted herein. His original, spiritual energy enlivens the material energy, and thus the dead body appears to have life force. Voidist philosophers think that under certain material conditions the symptoms of life occur in the material body, but the fact is that the material body cannot act on its own. Even a machine needs separate energy (electricity, steam, etc.). It is stated in this verse that the material energy acts in varieties of material bodies, just as fire burns differently in different wood according to the size and quality of the wood. In the case of devotees the same energy is transformed into spiritual energy; this is possible because the energy is originally spiritual, not material. As it is said, viṣṇu-śaktiḥ parā proktā [Cc. Madhya 6.154]. The original energy inspires a devotee, and thus he engages all his bodily limbs in the service of the Lord. The same energy, as external potency, engages the nondevotees in material activities for sense enjoyment. We should mark the difference between māyā and sva-dhāma — for devotees the sva-dhāma acts, whereas in the case of nondevotees the māyā energy acts.
Srimad Bhagavatam 4.9.7 Purport