Bhagavad Gita · Dhyana Yoga (Atma-samyama Yoga)Chapter 6, Shloka 7 (6.7)

"Paramātmā samāhitaḥ" — two readings.

Shankaracharya. Jitātmanaḥ … praśāntasya prasannāntaḥkaraṇasya sataḥ saṃnyāsinaḥ paramātmā samāhitaḥ sākṣād ātma-bhāvena vartate — for the self-conquered renunciate with a serene mind, the supreme self is present directly as their own self. And such a person samaḥ syāt — should remain even in all the pairs of opposites. Here mānāpamānayoḥ = pūjā-paribhavayoḥ — worship and contempt.

Acharya Ramanuja — "paramātmā" here is the individual self. Jita-manasaḥ vikāra-rahita-manasaḥ praśāntasya manasi paramātmā samāhitaḥ samyag āhitaḥ — in a calm mind free of agitation, the "paramatma" is well established. Then an important position: svarūpeṇa avasthitaḥ pratyag-ātmā atra paramātmā ity ucyate — here "paramatma" means the inner self (the jiva) established in its own nature, because tasya eva prakṛtatvāt — the context is about it, and pūrva-pūrvāvasthāpekṣayā paramātmatvāt — compared with its earlier states, it is "supreme". An alternative: ātmā paraṃ samāhita iti vā — "the self is fully composed" — "param" can also be read as an adverb.

The difference (philosophical): Shankara — the jiva and the paramatma are one, so "paramatma" directly; Ramanuja — the context is the vision of the self, so here "paramatma" = the pure individual self (not Ishvara).