'that's why' introduces a result: - It rained. That's why we got wet. (=It rained, so we got wet) 'that's because' introduces a reason: - We got wet. That's because it rained. (=We got wet because it rained)

Hi, Denise. The truth is it is difficult to explain the particular phrases that trouble you. However, they both answer the 'why' and are both used as conjunctions. Try out this link which might help you: http://www.towson.edu/ows/conjunctions.htm And check out these simplistic examples of mine: 1. You are always sweet, this is why I love you. 2. Their experiment failed... and that's because they didn't pay attention to minor details. 3. I hate maths; that's why I don't want to attend math classes. 4. She was left penniless. That's why she was unable to pay her bank debt. 5. I am being patient with you and that's only because you my son!

basically the same thing.

'That is why' would say that the first term causes the second term. That is because would mean that the first term is caused by the second term.