Bhagavad Gita · Jnana Vijnana YogaChapter 7, Shloka 19 (7.19)

"Vāsudevaḥ sarvam" — two readings.

Shankaracharya — all is Vasudeva alone. Bahūnāṃ janmanāṃ jñānārtha-saṃskārāśrayāṇām ante — at the end of many births spent gathering the impressions that lead to knowledge; jñānavān prāpta-paripāka-jñānaḥ mām vāsudevaṃ pratyag-ātmānaṃ pratyakṣataḥ prapadyate — one whose knowledge has ripened directly realises me, Vasudeva, as the pratyag-atma (one's own inner self); yaḥ evaṃ sarvātmānaṃ māṃ nārāyaṇaṃ pratipadyate saḥ mahātmā na tat-samaḥ anyaḥ asti adhiko vā — one who knows me, Narayana, as the self of all — there is no one equal to him, or greater. Further on: ātmaiva sarvo vāsudeva iti — the self is all; Vasudeva.

Acharya Ramanuja — everything is in Vasudeva. Vāsudeva-śeṣataika-rasaḥ ahaṃ tad-āyatta-svarūpa-sthiti-pravṛttiḥ ca — "my essence is to belong to Vasudeva; my nature, existence and activity depend on him"; and vāsudeva eva mama parama-prāpyaṃ prāpakaṃ ca anyad api yan manoratha-varti sa eva mama tat sarvam iti — "Vasudeva alone is my highest goal, he is the means, and whatever else the mind desires — he is all of that" — knowing this, he takes refuge. Vāsudevaḥ sarvam ity asya ayam eva arthaḥ — this is the very meaning of "Vasudeva is all"; evidence — the context (7.17, 7.18).

The difference (central): Shankara — oneness: everything (including the self) is Vasudeva alone; Ramanuja — one's all: for the devotee, Vasudeva alone is the goal, the means, and the object of every desire.