Bhagavad Gita · Akshara Brahma YogaChapter 8, Shloka 21 (8.21)

Shankaracharya. Tam eva akṣara-saṃjñakam avyaktaṃ bhāvam āhuḥ paramāṃ … gatim — that very unmanifest reality called akshara is said to be the supreme goal; tat dhāma sthānaṃ paramaṃ … mama viṣṇoḥ paramaṃ padam ity arthaḥ — that is my supreme state, the supreme state of Vishnu.

Acharya Ramanuja — two meanings of "dhāma". Paramagati-śabda-nirdiṣṭaḥ akṣaraḥ prakṛti-saṃsarga-viyukta-svarūpeṇa avasthita ātmā — "the supreme goal" here is the self freed from contact with prakriti and established in its own nature (the "supreme goal" of 8.13); evidence 12.3, 15.16. Tad mama paramaṃ dhāma paramaṃ niyamana-sthānam — my supreme sphere of governance (that over which I rule): non-conscious prakriti is the first, the jiva-nature bound up with prakriti the second, and mukta-svarūpaṃ paramaṃ niyamana-sthānam — the liberated self the third, the highest. An alternative: prakāśa-vācī dhāma-śabdaḥ … aparicchinna-jñāna-rūpatayā mukta-svarūpaṃ paraṃ dhāma — dhama = light, that is, the liberated self whose form is boundless knowledge. And further on: jñāninaḥ prāpyaṃ tu tasmād atyanta-vibhaktam — the goal of the wise one (the Lord) is entirely different from this (8.22).

The difference: Shankara — akshara = the supreme Brahman = the supreme state of Vishnu; Ramanuja — here akshara = the liberated self (kaivalya), and the goal of the wise one lies even beyond it, the Supreme Person (8.22).