The life of the saṅga is laid down in the rules of the Vināya-piṭaka, underlying the basic principles of poverty, chastity, and peacefulness. The bhikṣu relies on begging for his food, and his clothing, made of three parts (tricīvara), is preferably ragged. Initially, all bhikṣus spent their lives wandering, but were then allowed to spend the rainy season in a monastery (vihāra), which has now become the norm for the saṅgha. It is required (or at least desirable) that a layman should spend a period during the rainy season living as a bhikṣu.
The Buddha initially resisted the formation of an order of bhikṣuṇīs, fearing for distraction and moral disorder. But this was introduced by Mahāprajāpati Gautami, the Buddha's stepmother. There is no difference in principle between Theravada and Mahāyāna monastic observances, but the Mahāyāna list of precepts is longer. Mahāyāna bhikṣus observe 250 precepts while bhikṣuṇīs observe 348. Theravādin nuns adopt the habit and tonsure but observe only the ten precepts (Pāli, dassasīla) of the novice (Pāli, sāmaṇari) and are called dasasīlavanti, ‘those of the ten precepts’.
"Bhikṣu." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (September 21, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/bhiksu
"Bhikṣu." The Concise Oxford Dictionary of World Religions. . Retrieved September 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/bhiksu