When you have a psychic experience, you are within the astral reality.
The astral reality is the first layer of consciousness after the physical world.
When you dream, this is where your mind goes.
When you have a profound spiritual realization, you touch on a whole different level of energies:
You are beyond the astral within the causal (upper mental), buddhic or nirvanic planes of consciousness.
What are these planes of consciousness?
They are different levels of existence.
The beings or intelligences you connect with in these various levels rise from elemental beings on the astral level to spiritual masters on the causal plane to vast cosmic beings and avatars in the Buddhic realm.
If you jump to the nirvanic reality, you enter into the realms of Logoic entities like the solar or planetary logos.
All these experiences (psychic and spiritual) are related with the invisible.
Psychic experiences can be spectacular because they go beyond the usual limits of your awareness.
Right now, there is a window opened on the psychic realms.
The science of OBE's (Out of Body Experience) for instance is very complex and many people are actively researching techniques and directions along those lines.
The intentions and energies which sponsor these two directions (psychic and spiritual) have simply a different purpose.
It is like traveling in two different directions.
The field of psychic development can be compared to any other field of life experience. It has its own value and reason to exist.
It is however different from the path of spiritual development. The reason they are sometimes confused is because they both deal with the invisible.
The idea of New Age for instance is highly spiritual.
The worldly expressions of it (crystals, astrology, healing, music, etc) are actually psychic expressions of the original new age impulsion.
In the public's mind these two become one and this creates confusion.
If you make an internet search for "spiritual development", you will come across many psychic topics. You will hear about astral projection, auras and alien abductions where in fact these topics are not key spiritual development topics.
There is lots of confusion around that.
This is why it can be tricky to explore spiritual dimensions on your own: because the first layer you will encounter when trying to meditate is the astral.
If you meditate within a system, you use a "gate" which has already been established in the past.
This gate will take you beyond the astral realms and connect you straight with higher levels of consciousness (causal, buddhic and nirvanic).
Anything which has to do with visions, sounds, and colors is related with an astral experience. Sometimes, these experiences are related with a more profound spiritual experience.
The sounds or visions are only the "visible" part of this experience.
On the causal level, you will have experiences which are related with deep profound understandings and realizations.
You are still in the area where you can "mentalize" your experiences.
Causal means than you perceive the play of energies behind events and actions.
Basically, you perceive the "strings" and energies which organize life around you.
When you enter in the Buddhic realm, you go beyond the cycle of human evolution and reach the level of mastery of human life.
You not only see the dynamics, you are actually able to pull the strings yourself.
The only things you can perceive about nirvana are sensations like absolute bliss and total unification.
You go beyond sensory perceptions and simply merge with an infinite field of energy.
You enter a world beyond thoughts and emotions.
This is truly what is called enlightenment.
It can be a one time experience or a progressive increase of the nirvanic vibration.