Bhagavad Gita · Jnana Vijnana YogaChapter 7, Shloka 6 (7.6)

Shankaracharya. Ete parāpare kṣetra-kṣetrajña-lakṣaṇe prakṛtī yoniḥ yeṣāṃ bhūtānām — the field (apara) and the knower of the field (para) natures are the womb of all beings; therefore prakṛti-dvaya-dvāreṇa ahaṃ sarvajñaḥ īśvaraḥ jagataḥ kāraṇam — through the two natures I, the all-knowing Ishvara, am the cause of the world.

Acharya Ramanuja — "śeṣī". Brahmādi-stamba-paryantāni uccāvaca-bhāvena avasthitāni cid-acin-miśrāṇi sarvāṇi bhūtāni madīyāni — from Brahma down to a blade of grass, existing in higher and lower forms, all beings mixed of the conscious and non-conscious are mine; aham eva prabhavaḥ aham eva pralayaḥ aham eva ca śeṣī — I alone am the origin, I alone the dissolution, and I alone the śeṣī (the master, for whom everything exists). Evidence: Subala Up. (tamaḥ pare deve ekībhavati), Vishnu Purana 1.2.24 and 6.4.38–39.

The difference: Ramanuja's śeṣī–śeṣa (master–servant/part) relationship is the key to his philosophy; for Shankara, Ishvara is the cause, and (further on) one in the ultimate sense.