In Bhagavad-gītā (9.13) Lord Kṛṣṇa says:

mahātmānas tu māṁ pārtha daivīṁ prakṛtim āśritāḥ bhajanty ananya-manaso jñātvā bhūtādim avyayam

“O son of Pṛthā, those who are not deluded, the great souls, are under the protection of the divine nature. They are fully engaged in devotional service because they know Me as the Supreme Personality of Godhead, original and inexhaustible.” Mahātmās, advanced devotees, worship only the Supreme Personality of Godhead. Others, however, who are also sometimes called mahātmās, worship the Lord as ekatvena pṛthaktvena. In other words, they accept the demigods as different parts of Kṛṣṇa and worship them for various benedictions. Although the devotees of the demigods thus achieve the desired results offered by Kṛṣṇa, they have been described in Bhagavad-gītā as hṛta-jñānah, not very intelligent. Kṛṣṇa does not desire to be worshiped indirectly through the different parts of His body; Kṛṣṇa wants direct devotional worship. Therefore a devotee who directly worships Lord Kṛṣṇa through staunch devotional service, as recommended in Śrīmad-Bhāgavatam, ( tīvreṇa bhakti-yogena yajeta puruṣaṁ param ), is very quickly elevated to the transcendental position. Nevertheless, devotees who worship the demigods, the different parts of the Lord, receive the benedictions they desire because the Lord is the original master of all benedictions. If anyone wants a particular benediction, for the Lord to award it is not at all difficult.