Your link doesn't show anything wrong in what Dr Adequate posted. It just looks at a longer time frame, and if you include the massive outlier of September 11th 2001 (Dr A's graphic was looking at only the last decade) Islamic terrorists of course have killed the most. Your link notes, however, that over the same period right wing terrorists have killed more than left wing ones in the US.
I'm not really sure of the value of all these comparisons though. Very few people die due to terrorism. Whether or not one individual gets caught or changes their mind two minutes before carrying out their potentially devastating subway attack has enormous influence on the figures. Can't we just agree that terrorism is bad instead of using it to further polarise the American public?