Well, for me, spirituality means a belief that there is something otherworldly at work, and one’s belief in such. Whether that thing be a single God, multiple spirits or what have you, it doesn’t really matter, what matter’s is the belief in something outside the realms of science and logic that kind of help guide things in life and the movings of the world/universe.
Religion is the stepping stone that helps one achieve a greater sense of spirituality and helps one get close to whatever it is they feel they’re guided towards. For example, if you believe in God, and that you’re role in life is to gain a better understanding of what he/she/it wants for you out of this life and how to live it, then you’ve got hundreds of different religions that can help you out. To me, there is no one specific right, just many different avenues to travel to help get you to the appropriate destination.
Spirituality exists outside of religion. As does faith. Faith and spirituality are more connected and unified…religion is just a tool that one can either use as a fulcrum to focus their spirituality, or do without completely. some people use it as a crutch, some people let it overshadow their spirituality, and others ignore it completely.
As to why spirituality has become “more popular”…I hadn’t heard of that, but I know religion has become less popular. We live in an age of science and reason, and many feel the two can’t coincide. Plus, many religions used rather sketchy reasons to explain events and such that science is now able to explain, so it’s validity is a little off nowadays. Hence, it’s power has faded, and many people don’t really believe in religion anymore. But many of them still have faith. That’s my half-assed take on it.