Locally in Yorkshire there are the Clubman and the Centre Gradings. You only are graded if you compete on the Hard course at Centre Trials.
The Grades are Expert. They generally finish in the top 15% in the Centre Trials at least three times during a year. Intermediates in the top 30% three times. The Novice class is for new riders, and those who finish outside those criteria. Generally once you are in a class above novice you stay there for three years unless you move up. Experts not maintaining their status drop to Inter before dropping to Novice.
Usually there is also the Clubman class split into Adult, Over 40 and Over 50. These are riders who do not ride the main course due to inexperience, injury or age. There is usually a Harder course for the better Clubman these days it's a 50/50 with the Hard course but others a seperate course is laid
At Club Trial level these grades are kept and an Easier Clubman B course is usually plotted.
Novice Beginners are really for Clubmen and Beginners so are not that hard. Again though most have a A and B course for Clubmen.
Other Centres do it differently.