The difference between neophyte devotees and advanced devotees lays in how much they are interested in the missionary activities of the sankirtana movement for the benefit of others. Srila Prabhupada explains these important differences here:
"The demigods in the celestial heavenly planets, who are appointed administrators of the material affairs, are also devotees of the Lord. But at the same time they have desires for material opulence and sense gratification. The Lord is so kind that He awards them all sorts of material happiness, more than they can desire, but He is not satisfied with them because they are not pure devotees. The Lord does not want any one of His innumerable sons (the living entities) to remain in the material world of threefold miseries to perpetually suffer the material pangs of birth, death, old age and disease. The demigods in the heavenly planets, and many devotees on this planet also, want to remain in the material world as devotees of the Lord and take advantage of material happiness. They do so at the risk of falling down to the lower status of existence, and this makes the Lord dissatisfied with them.
Pure devotees are not desirous of any material enjoyment, nor are they averse to it. They completely dovetail their desires with the desires of the Lord and perform nothing on their personal account. Arjuna is a good example. On his own sentiment, due to family affection, Arjuna did not want to fight, but finally, after hearing Srimad Bhagavad-gita, he agreed to fight in the interests of the Lord. Therefore, the Lord is very much satisfied with pure devotees because they do not act for sense gratification but only in terms of the Lord's desire. As Paramatma, or Supersoul, He is situated in everyone's heart, always giving everyone the chance of good counsel. Thus everyone should take the opportunity and render transcendental loving service to Him wholly and solely.
The nondevotees, however, are like neither the demigods nor the pure devotees but are averse to any transcendental relationship with the Lord. They have revolted against the Lord and must perpetually undergo the reactions of their own activities.
The Bhagavad-gita (4.11) states, ye yatha mam prapadyante tams tathaiva bhajamy aham: "Although the Lord is equally kind to every living being, the living beings, for their own part, are able to please the Lord to either a greater or lesser extent." The demigods are called sakama devotees, or devotees with material desires in mind, while the pure devotees are called niskama devotees because they have no desires for their personal interests. The sakama devotees are self-interested because they do not think of others, and therefore they are not able to satisfy the Lord perfectly, whereas the pure devotees take the missionary responsibility of turning nondevotees into devotees, and they are therefore able to satisfy the Lord more than the demigods. The Lord is unmindful of the nondevotees, although He is sitting within everyone's heart as well-wisher and Supersoul. However, He also gives them the chance to receive His mercy through His pure devotees who are engaged in missionary activities. Sometimes the Lord Himself descends for missionary activities, as He did in the form of Lord Caitanya, but mostly He sends His bona fide representatives, and thus He shows His causeless mercy towards the nondevotees. The Lord is so satisfied with His pure devotees that He wants to give them the credit for missionary success, although He could do the work personally. This is the sign of His satisfaction with His pure, niskama devotees, compared to the sakama devotees. By such transcendental activities the Lord simultaneously becomes free from the charge of partiality and exhibits His pleasure with the devotees.
Now a question arises: If the Lord is sitting in the hearts of nondevotees, why are they not moved to become devotees? It may be answered that the stubborn nondevotees are like barren land or an alkaline field, where no agricultural activities can be successful. As part and parcel of the Lord, every individual living entity has a minute quantity of independence, and by misuse of this minute independence the nondevotees commit offense after offense, to both the Lord and His pure devotees engaged in missionary work. As a result of such acts, they become as barren as an alkaline field, where there is no strength to produce.