How do you tell who is a Buddhist monk or nun? You need to understand the process, here is the normal qualifications for both bhikshuni/bhikkhuni and bhikshu/bhikkhu. Women only follow the women's rules for Sangha, from the the bhikshuni lineage still extent to this day unbroken.
In the unbroken Dharmagupta lineage of the Vinaya precepts in the Mahayana traditions that have 2-part Vinaya Sangha:
Bhikshuni ordination is by application to an ordination committee. Bhikshuni are siksamana after 2 years living as a sramaneri (novice) with a qualified bhikshuni of acceptable years (Bhikshuni of rains age at minimum 5 but preferred is after 10 rains) before they are able to apply for full ordination. They must be resident Sangha in an acceptable monastic community before they apply for full ordination. Independent women living without training or preceptor both residing in the same temple are not accepted. Women who have lack of 2 years as siksamana are not accepted. Girls are not accepted, the full ordination age starts at 20 years old. Precepts are conferred in formal public way by first a bhikshuni ordination Sangha then a Bhikshu ordination Sangha. Both are usually 20 years into their own full precepts rains age. Bhikshuni and Bhikshu rains age begins on the day they become ordained, no matter how many years in robes before that, counts as age 0.
The Bhikshuni qualification for participation in giving ordination to siksamana is 12 rains age, the Bhikshu qualification to giving ordination is 10 rains age. The ordination group is usually very aged in rains and most committees are formed of at least 20 rains age for both and the age for the instructions is better after 20 rains because of the merit and virtue of being in purity so long is prized and seen as worthy accomplishment. There are monks and nuns who specialize in Vinaya and demonstrated they are capable instructors of new monks and nuns. This committee is made up of the present highly qualified bhikshuni and Bhikshu who self-directed their studies in the Vinaya and have practical experience in teaching newly arrived monks and nuns advancing their practice and keeping their purity as they age in rain years (rain years are the years spent in purity after you become a Bhikshuni or Bhikshu).
Countries with active Sangha: China, Taiwan, Korea, Vietnam, USA, England, the many South American countries, many European countries. Famous Buddhist countries with only Bhikshu Sangha: Thailand, Sri Lanka, Mongolia, Tibet.
