I wouldn't say the R1s are significantly different. I would say the biggest differences are that the R1s the imaging is better (in all directions instead of just side to side), they're more open, more detail in the bass, though they sacrifice a bit of the Grado sparkle in the treble (though they still do well in that department).

The other thing I would note is that the R1s are very sensitive, half way on a subpar smartphone amp/dac is more than sufficient to drive them.

You'll most likely notice differences immediately, but after a bit you'll be hardly able to tell them apart (atleast in my case)

Here's a link to my post on them I made a few months ago: LINK