We can see that the confusion about this simple subject - the bodies of man - has not begun with Theosophy, but always has been present in Hindu Classics. It is amazing that with so many sages none was able to explain clearly the matter. Things became clear to me only after reading C.W. Leadbeater and Alice Bailey books. Blavatsky made a tremendous mess about the subject.
About the difference between the etheric double and the astral body, it is very easy.
The Etheric Double is the Etheric part of the Physical Body. It is located in the Physical Plane.
The Astral Body, or Emotional Body, or Kama-Rupa (Kama=Desire)(Rupa=Form) is located in the Astral Plane, or Emotional Plane, or Kama-Loka (Loka=Place)
It is the plane above the Physical Plane, where people go when die.
From Wikipedia:
Kama
Kama in HinduismIn Hinduism, kāma is regarded as the third of the four goals of life (purusharthas, the others being duty (dharma), worldly status (artha) and salvation (moksha).[3][4] Kama-deva is the personification of this. Kama-rupa is a subtle body or aura composed of desire, while Kama-loka is the realm this inhabits, particularly in the afterlife. In the context of the four goals of life, kāma refers to mental and intellectual fulfillment in accordance to dharma.[5]
Theosophy: kama, kamarupa and kamalokaIn the Theosophy of Blavatsky, Kama is the fourth principle of the septenary, associated with emotions and desires, attachment to existence, volition, and lust.[9]
Kamaloka is a semi-material plane, subjective and invisible to humans, where disembodied “personalities[B]”, the astral forms, called Kama-rupa remain until they fade out from it by the complete exhaustion of the effects of the mental impulses that created these eidolons of human [/B]and animal passions and desires. It is associated with Hades of ancient Greeks and the Amenti of the Egyptians, the land of Silent Shadows; a division of the first group of the Trail?kya.