Yoga Sutras 3.7
Patanjali, explained by Swami Vivekananda
त्रयमन्तरङ्गं पूर्वेभ्यः ॥
trayamantaraṅgaṃ pūrvebhyaḥ
These three are more internal than those that precede.
In plain words: These three steps (concentration, meditation, absorption) are more inward than the earlier steps of yoga, like ethics, posture, breath control, and pulling in the senses.
Swami Vivekananda explains
Before these we had the Pratyāhāra, the Prānāyāma, the Āsana, the Yama and Niyama; they are external parts of the three — Dharana, Dhyana and Samadhi. When a man has attained to them, he may attain to omniscience and omnipotence, but that would not be salvation. These three would not make the mind Nirvikalpa, changeless, but would leave the seeds for getting bodies again. Only when the seeds are, as the Yogi says, "fried," do they lose the possibility of producing further plants. These powers cannot fry the seed.