These are so different, not just that one is a headphone and the other an IEM, but so drastically different that I wouldn't know where to start.
The JH13pro is very balanced in the low, mid and treble with a slight, very slight bass boost to give it that bass impact. The midrange is very balanced, not recessed or too forward and the treble perfect. The highs are not rolled off at all but are not harsh or edgy. It's perfect. The bass extends very, very low but has at the same time the bass impact that hits hard.
The JH13pro is both transparent, neutral and accurate and musical and fun. It's incredible that it does both.
Now the Grado RS1 is way more forward in the midrange and has the upper midrange and lower treble spike. The bass does not extend as low as the JH13pro but it does have a midbass hump that is wonderfully punchy and tight that gives the headphone a very fun involving feeling. The upper high treble on the Grado RS1 is shimmery, and detailed.
Grado RS1 unlike the JH13pro is unbalanced and extremely colored in its sound. JH13pro does everything well, all music, all genre...it falls short only to the HD800 in acoustic music. But it can do everything. The Grado RS1 because of it's upper midrange and lower treble spike does wonders for Rock (electric guitar and vocals).
Again, it's hard to compare. Even though the JH13pro is an IEM, it has a bigger headstage than the Grado RS1.
Maybe someone else can explain further what I've missed but hard to compare apple and oranges.