In the United States, there is almost always a strong course component to the degree. Most students are required to take at least two and as many as four seminars during their first year. This means that a PhD student will only actually begin his/her fields in year two and this would be followed by the dissertation. In the US, most PhD programs are considered to be four to five years long.
Canada usually represents a compromise between the UK and the US. Most Canadian universities will require that students take approximately two courses--usually during the first semester--and can begin their fields in the second semester. The program length is usually advertised as four years.