In Vishishtadvaita Vedanta, the relationship between the individual soul and the supreme soul is known as the relationship of "bheda-abheda" or simultaneous oneness and difference. This philosophy was propounded by the renowned philosopher and theologian, Ramanuja.

According to Ramanuja, the individual soul (jivatma) is a part of the supreme soul (paramatma) and they are inherently connected. The individual soul is not a separate entity but an inseparable part of the supreme soul, just like a wave is a part of the ocean. This means that the individual soul and the supreme soul share a fundamental oneness, but at the same time, they also maintain their individual identities.

Ramanuja explains this relationship through the concept of "sarira-sariri bhava" which means the relationship between the body and the soul. Just as the body is dependent on the soul for its existence and functioning, the individual soul is dependent on the supreme soul for its existence and actions. The individual soul is like a spark of consciousness, while the supreme soul is like a vast ocean of consciousness. This relationship is eternal and unbreakable.

The individual soul, being a part of the supreme soul, possesses all the qualities and attributes of the supreme soul, but to a lesser degree. This is known as "anvaya" or inherence. At the same time, the individual soul also has its own unique qualities and experiences, which differentiate it from the supreme soul. This is known as "vyatireka" or difference. This duality of oneness and difference is essential for the individual soul to have its own identity and experiences.

In Vishishtadvaita Vedanta, the ultimate goal is for the individual soul to realize its inherent oneness with the supreme soul and to unite with it. This is known as "moksha" or liberation. Ramanuja emphasizes that this union is not a merging of the individual soul into the supreme soul, but a loving and blissful relationship between the two. The individual soul retains its individuality even after attaining moksha, but its identity is completely immersed in the supreme soul.

In conclusion, the relationship between the individual soul and the supreme soul in Vishishtadvaita Vedanta is one of simultaneous oneness and difference. The individual soul is an inseparable part of the supreme soul and shares a fundamental connection with it, but also maintains its own unique identity. This relationship is eternal and leads to the ultimate goal of moksha, where the individual soul experiences the blissful union with the supreme soul.