Tea or not tea

A friend asked me about tea and the difference between tea and herbal tea.  For some this would be obvious, but for many it is not.  I tried to give them a brief  run-down in a message.  It is hard to do in 140 letters or less (I will not disclose if it was on my personal or business twitter account for privacy reasons).  I would like people to feel comfortable to ask those questions and that their privacy is respected.  I told the person that tea is from the camellia sinensis plant and contains caffeine.  I also mentioned that herbal tea can come from many different plants and usually contains no caffeine.  That was about all I could do in 140 characters or less and had to take out two "is" to get it to fit.  I wish I could have given him a little more thorough explanation, but also did not want to fill his message box with messages or ramble on forever.