Yes, they are all Avalokitesvara Bodhisattva.
In Chapter 25 of Lotus Sutra, 'The Universal Gateway of Observer of the World's Sounds (Avalokiteshvara) Bodhisattva', the sutra states of the different manifests that Avalokitesvara will appear in order to lead others to liberation.
Endless Intention Bodhisattva addressed the Buddha, saying, "World Honored One. Why does Observer of the World's Sounds Bodhisattva roam about in this Sahaa World? Why does he speak Dharma for beings? And what is the extent of the power of his skillful means?"
The Buddha declared to Endless Intention Bodhisattva, "Good Man, If there are beings in a country who ought to gain the crossing over to liberation assisted by the person of a buddha, then Observer of the World's Sounds Bodhisattva manifests the body of a buddha and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a pratyekabuddha, he then manifests the body of a pratyekabuddha and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a Hearer, he then manifests the body of a Hearer and speaks Dharma for their sakes.
"If there are those who ought to gain the crossing over to liberation assisted by the person of a Brahma Heaven King, he then manifests the body of a Brahma Heaven King and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of an Indra God, he then manifests the body of an Indra god and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of an Isvara Heaven god, he then manifests the body of an Isvara Heaven god and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a Great Isvara Heaven god, he then manifests the body of a great Isvara Heaven god and speaks Dharma for their sakes.
"If there are those who ought to gain the crossing over to liberation assisted by the body of a great heavenly general, he then manifests the person of a great heavenly general and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a Vaishrava.na, he then manifests the body of a Vaishrava.na and speaks Dharma for their sakes.
"If there are those who ought to gain the crossing over to liberation assisted by the person of a lesser king, he then manifests the body of a lesser king and speaks Dharma for their sakes. If there are those who ought to gain liberation assisted by the person of an elder, he then manifests the body of an elder and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a community leader, he then manifests the body of a leader of the community and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a government official, he then manifests the body of a government official and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a brahman, he then manifests the body of a brahman and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a bhikshu, bhikshuni, upaasaka or upaasikaa, he then manifests the body of a bhikshu, bhikshuni, upaasaka or upaasikaa and speaks Dharma for their sakes.
"If there are those who ought to gain the crossing over to liberation assisted by the person of the wife or daughter of an elder, community leader, government official, or brahman, he then manifests the body of such a wife or daughter and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation through the person of a boy or a girl, he then manifests the body of a boy or a girl and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the presence of a heavenly dragon, a yak.sa, a gandharva, an asura, a garu.da, a kinnara, a mahoraga, a human, a non-human, or some other, he then manifests the form of any one of them and speaks Dharma for their sakes. If there are those who ought to gain the crossing over to liberation assisted by the person of a vajra-holding spirit, he then manifests the body of a vajra-holding spirit and speaks Dharma for their sakes.There are many mantras by the Avalokitesvara Bodhisattva, in Chinese Mahayana the commonly chanted one is Great Compassionate Mantra (da bei zhou), in Tibetan Buddhism, the 6-syllable mantra Om Mani Padme Hum is often chanted.
Personally usually I just chant Na Mo Da Ci Da Bei Guan Shi Yin Pu Sa.
