philosophy
What is the difference between the individual soul (jiva) and the universal Self (atman or Brahman)?
What the words mean
Jiva means the living being, the soul as it appears in one person, with its body, mind, memories, and sense of "I". Atman means the Self, the pure awareness at the core. Brahman means the one reality behind everything. Much of Hindu philosophy turns on a simple question. Is the jiva, the little self, the same as that vast Self, or not? The famous line from the Chandogya Upanishad, tat tvam asi, often read as "that thou art", points to a deep link between the two. But how close that link is gets answered in very different ways.
Three main views
The schools do not agree, and each has long roots. Advaita Vedanta holds that there is really no difference at all. The jiva only seems separate because of limits, like a room of space that seems separate until the walls are seen as added on. Remove the limits, and the soul is Brahman, one and the same. Dvaita Vedanta holds the opposite. The jiva is always its own being, forever distinct from Brahman, even in liberation. The soul depends on the supreme but never becomes it. Vishishtadvaita takes a middle path. It uses the picture of body and soul. Just as your body belongs to you and is part of you yet is not the whole of you, the many souls belong to Brahman as part of one living whole, joined but not erased.
Why the debate exists
These views grew from teachers reading the same Upanishadic texts and weighing the same lines differently. Some verses sound like "all is one", others sound like "the soul and the Lord are two". Each school built a careful reading to hold its side together. The disagreement is real and old, and the tradition has lived with it for centuries rather than settling on one answer.
How people hold it today
For many people this is not just abstract. Those drawn to Advaita feel comfort in the idea that the deepest self is never lost. Those drawn to devotion often prefer a view where the soul stays distinct, so love between the soul and the divine still makes sense. Many simply use the word atman for the inner self and Brahman for the whole, without picking a fixed side. Which view feels true tends to follow a person's path and temperament.