When a devotee gets liberation, he becomes free from material contamination and engages as a servant of the Lord. This is explained in Srimad-Bhagavatam (2.10.6): muktir hitvanyatha rupam svarupena vyavasthitih. The word svarupa refers to sarupya-muktigoing back home, back to Godhead, and remaining the Lords eternal associate, having regained a spiritual body exactly resembling that of the Lord, with four hands, holding the sankha, cakra, gada and padma. The difference between the mukti of the impersonalist and that of the devotee is that the devotee is immediately appointed an eternal servant of the Lord, whereas the impersonalist, although merging in the effulgence of the brahmajyoti, is still insecure and therefore generally falls again to this material world. Aruhya krcchrena param padam tatah patanty adho nadrta-yusmad-anghrayah (Bhag. 10.2.32). Although the impersonalist rises to the Brahman effulgence and enters into that effulgence, he has no engagement in the service of the Lord, and therefore he is again attracted to materialistic philanthropic activities. Thus he comes down to open hospitals and educational institutions, feed poor men and perform similar materialistic activities, which the impersonalist thinks are more precious than serving the Supreme Personality of Godhead. Anadrta-yusmad-anghrayah. The impersonalists do not think that the service of the Lord is more valuable than serving the poor man or starting a school or hospital. Although they say brahma satyam jagan mithyaBrahman is real, and the material world is falsethey are nonetheless very eager to serve the false material world and neglect the service of the lotus feet of the Supreme Personality of Godhead.