Firstly there is section which is the standard Easy, Normal, Hard, Ex/Super Hard, and Master. The thing they share in common is speed of notes. (Super Hard/Daily Songs songs are the exception since they are made to be harder than the section they are placed in.)
Secondly there is the star system which is a scale of one star to the current maximum of twelve stars. This scale is more specific of the difficulty level since it's more of an exact reading of how hard it is.
- Easy Section is at a slow pace with a star rating of 1~4 stars.
- Normal Section is at a more moderate, still kind of slow but not much, pace with a star rating of 4~7 stars.
- Hard Section is at an sightly faster than average pace with a star rating of 6~8 stars.
- Expert Section is at a fast pace with a star rating of 9~10.
- Master Section is at an extreme pace with a star rating of 11~12 stars.
Note: Daily songs are 1~2 stars above the section they are placed in.