There is a very fine difference between people's understanding of spirituality and religion. What many people consider most of the times is that spirituality and religion are correlated, but they are not.
Let's have a look at both of them separately:
Spirituality is the 'quality of being concerned with the human spirit or soul as opposed to material or physical things'. What does this mean- the soul is the most profound form of someone's being. There is nothing deeper, nothing more abstract than the soul. A human being's soul directs him/her to establish certain ideas in life. Thus, for practicing spirituality, one needs to be content with his/her soul.
What spirituality actually does is that it cleanses our very soul. We may understand this wit an example: Just as we plant a seed and it doesn’t grow into a plant all by itself. We have to nurture it in sunlight, water it and then after a proper amount of time after handling it with care it blossoms into a full plant. Similarly, we may see the case with a human soul. Our soul doesn’t nurtures itself on its own. There is a driving force behind it which we may call spirituality. It is functioned in our conscience through optimism, self-care, realization of others’ need and taking care of one’s surroundings, sense of gratitude. Thus, we may understand it as something which gives meaning to life, which is beyond the definition of what we read in books and scriptures. It could be practiced with/without anyone’s help and does not necessarily mean to be followed from any textual form. It comes from within one’s conscience.
Religion is one’s belief in the Supreme source of being, i.e. God or various forms of God. What we find most of the times is that a particular religion is followed with the help of scriptures, sacred books, teachings of Gurus, and other forms. It may or may not lead a person to follow his inner conscience, because it has been seen that in many cases people prefer to follow what is written in their texts rather than what they themselves believe in.
For practicing spirituality one doesn’t need to read any sacred holy books or texts, but for knowing about and practicing religion one must be aware of his/her religious texts.
Also, one could be very spiritual and yet not want to be religious, and one could have thorough knowledge of texts and may practice his/her religion but not be very spiritual.