I hate to burst your bubble but computer animation is not a style of movie only a technique used for: "real-time 3D rendering (often used in video games), video capture and video creation rendering, special effects editing (often used for movies and television), image editing, and modeling (often used for engineering and medical purposes)."
If I can quote myself:
What your discussing is not the definition of Anime but a sub-genre of Anime known as BESM (big eyes small mouth).Well according to Wikipedia:
Anime is Japanese animation, often characterized by stylized colorful graphics depicting vibrant characters in a variety of different settings and storylines, aimed at a variety of different audiences... Internationally, anime once bore the popular name Japanimation, but this term has fallen into disuse. It saw the most usage during the 1970s and 1980s, which broadly comprise the first and second waves of anime fandom. The term survived at least into the early 1990s but seemed to fade away shortly before the mid-1990s anime resurgence. In general, the term now only appears in nostalgic contexts. The term Japanimation is much more commonly used in Japan to refer to domestic animation. Since anime or animeshon is used to describe all forms of animation, Japanimation is meant to distinguish Japanese work from that of the rest of the world..
There is no such thing definitivly as "American Anime" (or in this case "CG movies") there is just animation. The real question is whether it is "anime" or an "animated cartoon".
Animated cartoons are usually shown on television or cinema screens and are created by drawing thousands of individual drawings which are shown rapidly in succession to give the impression of movement. In this meaning, the word cartoon is often shortened to toon, which may be a corruption of Looney Tunes. Toon was popularized in the movie Who Framed Roger Rabbit?. Toons are often anthropomorphized animals used in non-serious fiction. It is not generally used to in reference to anime characters. A major distinction between the two is the squash and stretch mannerism of American cartoon characters.
Of course Advent Children is Anime, it's animated. Likewise the FF movie is Anime also, just CG animation. That doesn't make FF RPG's an Anime though. Is either of them BESM? No.