The difficulty is the measurement of how hard the song is the rating of how hard a song is to play. There are two different scales of difficulty.
Firstly there is a 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.
- 1-3 stars are colored in green. The difficulty indicates that the song is easy. None of the star ratings are placed in Normal. None of the songs with these star ratings will have starred notes in them.
- 4-6 stars are colored in yellow. The difficulty indicates that the song is normal. Unless songs with a star rating of 4 are placed in easy difficulty and the daily songs, the songs will have starred notes in them. Some songs have a rating of 6 that are placed in hard.
- 7-9 stars are colored in orange. The difficulty indicates that the song is hard (exception for 9 as it's expert). Some songs have a rating of 7 stars that are placed in normal. There is no difference except speed as normal have starred notes. Some songs with a rating of 9 stars are in Expert and not Hard.
- 10 stars are colored in pink. The difficulty indicates that the song is very difficult (expert to master). Some songs with a rating of 10 stars are in Expert. Some of the easier expert songs will have a rating of 10 stars in Master. Those songs do not have slide notes.
- 11 stars are colored in purple. The difficulty indicates that the song is very difficult (master). Songs with 11 stars only appear in Master mode and some of the harder random songs. Daily songs are the exception. Most songs will not have slide notes, but some do.
- 12 stars are colored in hot pink. The difficulty indicates that the song is at it's hardest level (master). Songs with 12 stars only appear in some songs in Master Mode. Some of the songs do have slide notes, some will not.
- 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 a slightly 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 10~12 stars. Only 11 and 12 stars will include slide notes depending on the difficulty.
Note: Daily songs are 1~2 stars above the section they are placed in.