Whatever abode is reached by Sāṅkhya (yoga), that is attained by Yoga (Karma-yoga) too. He who sees Sāṅkhya path and Yoga path as the same, alone has the right vision.
Krishna re-states and confirms that Sāṅkhya, meaning wisdom-path, and Yoga, meaning Karma-yoga path are essentially the same pursuit.
Sāṅkhya-yoga instils introspection on the imperishable Self, and on sukha-duḥkha caused by interactions. The focus is extended to all pairs of opposites, which produce sukha-duḥkhas alone. Sāṅkhya thus means to meet dvandvas with equipoise.
Karma-yoga emphasizes pursuing karmas, which bring favourable, unfavourable and admixed results. Assimilate all of them and be unaffected, equipoised.
Focus in both pursuits is internal, not external. Mind and intelligence alone are applied for Sāṅkhya and Yoga. In Sāṅkhya, it is on sukha-duḥkha samatva. In Yoga, it is on siddhi-asiddhi-samatva (equipoise). As sādhanā advances, their difference will narrow down and finally be extinct, making the seeker fulfilled.