Yes. I suppose in mangled New Age jargon, this is all the same.
The 3rd eye refers to the ajna chakra of Tantric yogic lore. It means “commanding” and corresponds with the pituitary gland and the nasobasillary plexus. It is supposed to represent that aspect of the psyche that is intelligible and intuitive. I’ve heard people talking about “opening” their third eye or “projecting” out their third eye. Whatever. I worked with chakras for decades and I don’t go in for this kind of chatter. The chakra points correspond to a neurochemical loop in the brain that you prime when you meditate on the chakras in a certain way. One chakra is not more special than other. The pathway has be built as a whole.
Astral projection is caused by a usually benign seizure-like activity (that can be learned by healthy persons or else frequently occurs in the context of epilepsy and schizophrenia) that occurs often in the parietal lobe of the brain. A person feels disassociated from body and location and experiences themselves from perspective outside the body. Combined with trance states and lucid dreaming, some people use this as a technique for spiritual or occult experiences and learning.