Here you go. Firstly, the shape is pretty different. The Grasshopper GTX is more of a rounded V shape whereas the the Orbital GTX is a harsher W shape. The Grasshopper GTX weighs in on my scale as 66g w/ bearing and string while the Orbital GTX weighs in at 64g w/ bearing and string. My scale measures in 0.5g increments so take those weights with a grain of salt, but suffice it to say that the Grasshopper GTX is roughly 2g heavier than the Orbital GTX.
On the string, they also play pretty different. They both have power and presence on the stringāthey feel like Duncan bimetalsābut the Grasshopper GTX plays like powerful and fastāsimilar to the Haymaker Xāwhile the Orbital GTX plays a little less powerfully and slightly slower (though itās still plenty powerful). The Orbital GTX feels wider by comparison even though itās not actually that much wider. I think thatās because the Grasshopper GTX has narrower rings that focus their weight on the rims to make a really powerful throw whereas the Orbital GTXās wider rings probably spreads the weight over a larger area.
I hope that helps!
Edit: changed āthinner ringsā to ānarrower ringsā with reference to the Grasshopper GTX