In the Mahayana Uttara Tantra Shastra (translated as 'The Changeless Nature'), it is explained that even though there is only one moon in the sky, it is reflected many times in pools and oceans, in clear or dirty water. Just like that example, Amitabha's activity permeates everywhere. The dharmakaya appears everywhere, dependent on the clarity of one's mind. If the water is agitated, the moon will still reflect in it, but unclearly. It is the same with one's mind: if the mind is agitated, the dharmakaya is not clearly revealed. That concludes the praise and homage to the dharmakaya.
Amitabha's speech is called Vajra Speech as it is unceasing. In terms of the quality of his speech, it is unequalled even by the sound of thunder, and also it is very beautiful, like melodious song or music. When the Buddha teaches, to those nearby his speech does not sound loud, but pleasant and clear, yet those listening far away can also hear it clearly. If one is listening to Amitabha's speech, it never sounds unpleasant, and it possesses 60 special qualities unmatched by melodious song. Rinpoché thinks that this is why the 2 examples, of his voice being unmatched by thunder and melodious song, are given in the sadhana. Out of compassion for all beings, Amitabha continually gives Dharma teachings. That is the praise and homage to the sambhogakaya.
There follows a praise to Amitabha's Vajra Mind, which is endowed with the 2 qualities of knowing the nature of things just as they are, and the many things that are to be known. It is a mind that cares for the welfare of all beings continually with great compassion and impartiality. Even though Brahma is a lord of a thousand million worlds, and Indra is powerful and has great merit, their minds cannot equal the mind of a buddha. One pays homage to Amitabha's mind, residing in a nirmanakaya form. In the text, it describes Amitabha as nirmanakaya, sambhogakaya or dharmakaya. These 3 are simply different aspects of forms. Each kaya has 3 different facets. For example, the dharmakaya of dharmakaya is Buddha Samantabhadra; the sambhogakaya of dharmakaya is Vajradhara; the nirmanakayas of dharmakaya are the 5 lords of the buddha-families. So, Amitabha, as head of the Lotus family, is classified here as nirmanakaya. The dharmakaya of sambhogakaya is Vajradhara; the sambhogakaya of sambhogakaya is Vairochana Gangchentso; the nirmanakaya of sambhogakaya is Sakyamuni Buddha. The dharmakaya of nirmanakaya is Amitabha; the sambhogakaya of nirmanakaya is Chenrezig; the nirmanakaya of nirmanakaya is Guru Rinpoche. So, here, Amitabha is the dharmakaya. http://www.purifymind.com/Amitabha.html