The following from the Reference Manual....

Arpeggio Type Name
The Arpeggio Types are named according to certain rules and abbreviations. Once you understand these rules and abbreviations, you’ll find it easy to browse through and select the desired Arpeggio Types.

Arpeggio types with “_N” at the end of the type name (example: HipHop1_N)
These Arpeggios are for using with the Normal Part, and Arpeggios with complex notes can be created even when triggered by one note.

Arpeggio types with “_C” at the end of the type name (example: Rock1_C)
These Arpeggios are for using with the Normal Part, and correct Arpeggios can be created corresponding to the chord you play.

Arpeggio types with a normal name (example: UpOct1)
In addition to the above types, there are three playback types: the Arpeggios created for use of Normal Parts and played back using only the played notes and their octave notes, the Arpeggios created for use of Drum Parts, and Arpeggios containing mainly non-note events.

Arpeggio types with “_AF1”, “_AF2”, or “_AF1&2” at the end of the type name (example: Electro Pop AF1)
When these Arpeggios are played, both of [ASSIGN 1] and [ASSIGN 2] buttons are automatically turned ON and the phrase starts playback.

Arpeggio types with [Mg] at the beginning of the type name (example: [Mg]HardRock1)
These Arpeggios are for using with a Mega Voice.

Mega Voices and Mega Voice Arpeggios
Normal sound uses velocity switching to make the sound quality and/or level of a Part change according to how strongly or softly you play the keyboard—giving greater authenticity and natural response to these Parts. However Mega Voices have a very complex structure with many different layers that are not suitable for playing manually. Mega Voices were developed specifically to be played by Mega Voice Arpeggios to produce incredibly realistic results. You should always use Mega Voices with Mega Voice Arpeggios.

Normal Parts have the following three playback types.
1_ Playback of played notes only
The Arpeggio is played back using only the played note(s) and octave notes.

2_ Playback of a programmed sequence according to the played notes
These Arpeggio types have the several sequences each of which is suited for a certain chord type. Even if you press only one note, the Arpeggio is played back using the programmed sequence— meaning that notes other than the ones you play may be sounded. Pressing another note triggers a transposed sequence using the pressed note as the new root note. Adding notes to those already held changes the sequence accordingly. Arpeggios with this playback type have “_N” at the end of the type name.

3_ Playback of a programmed sequence according to the played chord
These Arpeggio types created for use with Normal Parts are played back to match the chord type determined by detecting the notes you play on the keyboard. Arpeggios with this playback type have “_C” at the end of the type name.

NOTE: When the “Key Mode” parameter is set to “Sort” or “Sort+Drct,” the same sequence is played back no matter what order you play the notes. When the “Key Mode” parameter is set to “Thru” or “Thru+Drct,” a different sequence is played back depending on the order you play the notes.
NOTE: Since these types are programmed for Normal Parts, using them with Drum Parts may not produce musically appropriate results.