The karmīs, who are much attracted by the fruitive activities of the Vedic rituals, are called bhukti-kāmī, or those who desire material enjoyment.
The jñānīs, who try to become one with the Supreme by mental speculation, are called mukti-kāmī, or those who desire liberation from material existence.
The mystic yogīs, who practice different types of austerities for attainment of eight kinds of material perfection and who ultimately meet the Supersoul (Paramātmā) in trance, are called siddhi-kāmī, or those who desire the perfection of becoming finer than the finest, becoming heavier than the heaviest, getting everything desired, having control over everyone, creating everything liked, etc. All these are abilities of a powerful yogī.
But the devotees of the Lord do not want anything like that for self-satisfaction. They want only to serve the Lord because the Lord is great and as living entities they are eternally subordinate parts and parcels of the Lord. This perfect realization of the self by the devotee helps him to become desireless, to desire nothing for his personal self, and thus the devotees are called niṣkāmī, without any desire. A living entity, by his constitutional position, cannot be void of all desires (the bhukti-kāmī, mukti-kāmī and siddhi-kāmī all desire something for personal satisfaction), but the niṣkāmī devotees of the Lord desire everything for the satisfaction of the Lord.
(Source: SB 2.4.18 - Purport)
