Pūjā means I call you and offer you some respectable (indistinct), some foodstuff, and then very much seated very comfortably. Naturally I may ask, "What do you want?" Then I’ll explain, "Give me this. Give me that. Give me that." That is going on. That is called pūjā.
But those who are worshiping the Supreme Personality of Godhead, that is not called pūjā; that is called sevā, kṛṣṇa-sevā. We never say kṛṣṇa-pūjā. Nobody… Never says like that. Sevā. Sevā means it is my duty. I am eternal servant of Kṛṣṇa. Sevā is my duty. So there is difference between pūjā and sevā.
Pūjā means I flatter you to satisfy you, and after being satisfied, you may offer me something, or I’ll ask you something and you offer me. That is called pūjā. That is devatā-pūjā. But, so when you come to Kṛṣṇa, or Viṣṇu, that is not pūjā; that is sevā. Sevā. So as Kṛṣṇa is offered sevā, service, similarly His representative, he is also offered sevā.
Srila Prabhupada - Lecture on Śrimad Bhāgvatam, October 22, 1976, Vrindavan