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. 