Staring at a Tree

Okay, so here is a not-so-interesting-or-creative-story, but it should bring up a good point of discussion:

A man was walking home one day, when he noticed two women staring at a tree. The man was curious (and a bit nosy too), so he walked over to the ladies.

"Why are you staring at that tree," asked the man.

The short lady said, "we are having a debate over whether this tree was created by God or if it is the product of millions of years of evolution. I think that God created all things, including this tree."

"But I do not believe that God exists and I think that this tree is a product of chance," responded the tall lady.

The man was still puzzled: "Well, if both of you are looking at the same tree, why do you come to such different conclusions? You are both looking at the same tree aren't you?

"Of course we are looking at the same tree!" responded the ladies in unison.

Bewildered by the series of events, the man continued to make his way home, while the women continued to stare at the tree.

So, here is where the discussion comes in. If the women are looking at the same tree (i.e. they are observing the same "facts"), how do you explain their disagreement? What is the source of their differing opinions?