What is the difference between "mass" (touching/contact) and "lams" (touching/feeling) as stated in the Holy Quran (None shall touch it except the purified)?

"Al-lams" (touching) and "al-mass" (touch/contact) are close in meaning, and one may be used to express the other. The subtle difference between them is: "Al-lams" is perception with the surface of the skin, and it is used to express seeking or sexual intercourse. "Al-mass" is said concerning that which involves perception by the sense of touch, and it is used euphemistically for sexual intercourse and its preliminaries, for madness, and for any harm that befalls a person.