Because ihram is a state rather than a costume, it comes with a list of things suspended for its duration, and with a graded system of compensation for breaking them.
The prohibitions are specific. No cutting of hair or nails. No perfume, including scented soap. No hunting or assisting a hunt, and no killing of game. No contracting of a marriage, and no sexual relations. No quarrelling or obscenity. Men do not cover the head or wear sewn garments fitted to the body; women dress ordinarily and modestly but, on the majority view, do not cover the face with a fitted veil or wear gloves, which is one of the few contexts in which face covering is restricted rather than required.
Compensation is called fidyah or, in the more serious cases, dam. Its structure comes from an incident preserved in the hadith: Kab ibn Ujrah was in ihram with a scalp complaint aggravated by lice, and was permitted to shave, with the choice of fasting three days, feeding six poor people, or offering a sheep. That triad became the model. Lesser breaches attract the fidyah option; killing game attracts a compensation matched to the animal; and sexual relations before the standing at Arafat invalidate the Hajj altogether, requiring it to be repeated as well as expiated.
The white cloths themselves carry the meaning most pilgrims report as the strongest. Unsewn, unmarked and identical, they remove every indication of nationality, wealth and rank from several million people at once, which is the visual argument the Hajj makes about equality before God.
Entering ihram requires the intention, the niyyah, and the talbiyah, the declaration beginning here I am. Without the intention the garments are only cloth.