That is because what you are finding is from the old classification system which is still widely distributed on the net The newer system which identifies  subspecies within the United States as opposed to  odd lumps many groups including the original Great Plains wolf population which was thought to have become extinct into a single Canis lupus nubilis otherwise called the Plains wolf Great plains wolf or Buffalo wolf This like is illustrated on the map ranges throughout Eastern Canada and North East USA The reason many sources will say it is the Eastern timber wolf I believe is mainly to help conservation Not only does the name seem more attractive to residents therefore they are more likely to want to preserve it but this wolf is comparitively vulnerable in its smaller range Another confusion may be because Eastern timber wolves used to live in this area but were killed off due to the bounties It was then the other subspecies the Plains wolf which eventually reinhabited the North Eastern states When I have more time I will try to finda reliable source forthis