How are these (the 5 elements in Celtic tradition) different from what you may already be familiar with?

I don't think the first four are very different at all.  Earth, Wind, Air, and Fire are common in all traditions I've seen or studied.  Even the element of Spirit is similar to other beliefs.  In the Celtic tradition explained here, though, it is slightly different — and more realistic to me.   I'm drawn to the fact that it includes the Spirit of humans, and not just the Divine.  I believe we are all connected to the Divine, and this view of the elements reinforces that belief in me.