Bhagavad Gita · Raja Vidya Raja Guhya YogaChapter 9, Shloka 9 (9.9)

Shankaracharya. udāsīnavat āsīnaṃ yathā udāsīnaḥ upekṣakaḥ kaścit tadvat, ātmanaḥ avikriyatvāt — like a neutral onlooker, because the self is changeless; asaktaṃ phalāsaṅga-rahitam abhimāna-varjitam "ahaṃ karomi" iti — free of attachment to fruit and of the pride "I am the doer"; and the teaching: ataḥ anyasyāpi kartṛtvābhimānābhāvaḥ phalāsaṅgābhāvaś ca asaṃbandha-kāraṇam, anyathā karmabhiḥ badhyate mūḍhaḥ kośakāravat — so for anyone else too, the absence of the pride of doership and of attachment to fruit is the cause of freedom; otherwise the deluded person is bound by his own actions like a silkworm in its cocoon.

Acharya Ramanuja — inequality comes from the actions of beings. Na ca tāni viṣama-sṛṣṭy-ādīni karmāṇi … mayi nairghṛṇyādikaṃ na āpādayanti — an unequal creation does not bring cruelty into me; yataḥ kṣetrajñānāṃ pūrva-kṛtyāni eva karmāṇi devādi-viṣama-bhāva-hetavaḥ — because it is the past actions of the beings themselves that cause the unequal conditions, as gods and so on; ahaṃ tu tatra vaiṣamye asaktaḥ … udāsīnavad āsīnaḥ. Evidence Brahmasutra 2.1.34–35 (vaiṣamya-nairghṛṇye na sāpekṣatvāt; na karmāvibhāgād iti cen nānāditvāt).

The difference: Shankara — a teaching of non-attachment (for everyone); Ramanuja — a theodicy: the cause of inequality is the beginningless karma of beings.