American is typically more mild in taste and smoother than cheddar; unless we are talking Kraft Singles American, which is a smoother or creamier cheddar.
It does have emulsifiers and other dairy products in it. It has a higher moisture content, which the emulsifiers help to hold in suspension with the cheese. Without the emulsifiers the cheese would leak water/fluid out and the shelf life would be considerably shortened. The emulsifiers used are very common in many foods from almond milk to soft drinks.