There's a difference between normal vampires and psi vampires, normal vampires feed of blood, psi vampires feed of energy from other human beings while a conduit absorbs energy mostly from their surroundings.
Psi Vampires are normal human beings with one or more defective or dysfunctional chakra (relative to normal human beings), which means the chakra can't produce enough of its own energy causing an imbalance in that person’s life force. It's a condition psi vampires are born with and in order for the affected person to function properly, that person needs energy from another source. Normal human beings may contract vampirism during their life time through drawn out stressful events, prolonged association with vampirism or from a detrimental psychic attack.
Not getting enough energy can lead to ailments which includes but is not exclusive to emotional, neurological, mental and physical instability. Not only psi vampires feed of energy, normal human beings does it as well in times of illness and injury as a way of survival, what separates normal people from psi vampires is the fact that psi vampires will continue feeding of energy even when in perfect health and will suffer from the above mentioned ailments when not getting a stable supply of energy. Conduits on the other hand will absorb energy from their surroundings and instead of feeding on it; they will simply keep it until another psi vampire drains it (acting as a donor) or until the conduit decides to ground it. If they fail to get rid of the absorbed energy, they will experience similar symptoms to that of a hungry psi vampire whereas a psi vampire will experience these symptoms when operating in an energy deficiency.
For people saying they’re getting a headache when not feeding of other people’s energy might be imagining it, furthering the illusion that they are in fact a psi vampire, real symptoms are intense and crippling. The main difference between an individual with an actual vampiric condition and a normal person is the fact that regardless of how much work is done to fix the problematic area (referring to the aura); a true vampire will not be able to fix it permanently (only temporary relief is possible).
Also note that there’s a big difference between psi vampire and psychic vampires, psi is the shortened form of psionic, some psionic vampires do have psychic abilities, but psionic mostly refers to the natural ability to manipulate and sense energy, lots of psionic vampires do so on a subconscious level on a daily basis and thus need the extra energy.
Psi vampires have the ability to directly connect to another person through a direct link, this can be used for feeding (which is dangerous for several reasons), and it can be used for healing or sharing information directly. Besides being able to connect to another person, other abilities include being generally psychic, ability to manipulate energy, the ability to heal others and oneself, the ability to slow the aging process in rare cases, proficiency at astral projection, high sensitivity to surroundings, highly empathetic and the ability to physically see auras.
Vampires are usually night people on a biochemical level. They have inverted circadian rhythms, with body cycles such as temperature peaks, menstrual onset, and the production of sleep hormones in the brain occurring at the opposite time of day from most people. They have difficulty adjusting to daytime schedules and frequently work at night. They tend to be photosensitive, avoiding sunlight, sun burning easily, and having excellent night vision. Their vitality ranges widely, and they can be vigorous and active one day, depressed and languorous the next.
Many people find that they feel "creepy" or "weird" around a vampire. This is usually due to the effects of one's own life force being drawn towards the vampire's vortex. Most people feel uncomfortable and distracted when their energy is pulled away from themselves. In addition to this, a common result of such an energy drain is for the aura to pull in tightly towards the body, and this causes a prickling sensation on the skin.
Just my 2c