The sequencer records two levels[1], accented and un-accented, depending on the velocity you strike the key with - I think the threshold is at 64.
When playing back using the Play button, those levels are 127 and 64. When playing back from the keyboard they're 127 and whichever velocity you struck the key with.
[1] I don't know what the sequencer actually records, only what it outputs... :p