How a sotapanna person experiences the mind? What is the difference between lay person and a person who achieves sotapanna?Does sotapanna person experience less thoughts?Would they experience as dukka,happiness,pain like mind states?
Maybe the simplest answer to this question is that a sotāpanna does experience the mind, whereas most people identify with the mind so strongly that they cannot experience it at all. They are immersed in their thoughts, emotions, and urges, and cannot effectively separate themselves from these mental conditions.

Someone is sotāpanna when they have eliminated the following three obstructions:


Self-view
Clinging to rites and rituals
Skeptical doubt


The first — the elimination of self-view — means that they have abandoned the idea that the self is intrinsically bound to the 'five aggregates': physical forms, feelings or sensations, perceptions, mind structures, and discriminative thinking. All of these still arise in a sotāpanna, but the sotāpanna realizes that these are not identical to him/herself. For instance, imagine a man who feels a sudden wave of hatred towards something. If he is unskilled he merely hates, with no qualifiers; if he has the skills of a sotāpanna he recognizes the hatred as something separate arising within his mind. He may still be controlled by it because his attachments are still strong, but he has created a certain spaciousness — a mental distance from the arising — that he can cultivate with further practice. As he progresses, this spaciousness grows and those arisings weaken.

Sotāpanna is just the first step, and there's no sense expecting the unconscious habits of a lifetime to fall away like dead leaves. So yes, dukkha and tanhā will still be there; the mind will still be filled with thoughts and feelings and urges. We have to get into the water first, and only after that can we start to learn how to swim. But getting into the water is an accomplishment.