What is the difference between the 180 and 225?
Rocking the Note 4
Basically the shape of the adapter itself... The 180 appears to be a bit more straight (see pic below)
And the 225 is actually "stepped" so the adapter exits and clears the Moto 360 housing and then bends towards your wrist (see a 225 pic below). Obviously, manufacturing and crafting the angled 225 adapter is quite a bit more challenging, which is probably why it wears the larger price tag.
I considered getting both to better show the difference and see which I liked better, however I wasn't sure I was even going to like it. Add to that the cost of these adapters and the fact that I have rather thin / small wrists and I felt the 225 would work better for me. After a full day's use wearing it, I'm liking it! It's comfortable, fits perfectly and doesn't bind up or bite into my wrist (like I feared).
Whichever one you pick, keep in mind that both of these are made from stainless steel. A material that will most likely hold up to some punishment and should allow you to experiment with many different watch bands.