CC Madhya 20.184
vilāsa, svāṁśera bhede vividha vibheda
“In the tad-ekātma-rūpa there are pastime expansions [vilāsa] and personal expansions [svāṁśa]. Consequently there are two divisions. According to pastime and personal expansion, there are various differences.
The Lord’s vilāsa expansions are described in the following verse from the Laghu-bhāgavatāmṛta (1.15):
prāyeṇātma-samaṁ śaktyā sa vilāso nigadyate
“When the Lord displays numerous forms with different features by His inconceivable potency, such forms are called vilāsa-vigrahas.”
The Lord’s svāṁśa expansions are also described in the Laghu-bhāgavatāmṛta (1.17):
saṅkarṣaṇādir matsyādir yathā tat-tat-svadhāmasu
When a form of Kṛṣṇa is nondifferent from the original form but is less important and exhibits less potency, it is called svāṁśa. Examples of svāṁśa expansions can be found in the quadruple forms of the Lord residing in Their respective places, beginning with Saṅkarṣaṇa, Vāsudeva, Pradyumna and Aniruddha, and also in the puruṣa-avatāras, līlā-avatāras, manvantara-avatāras and yuga-avatāras.