They both work the same on Moto360 and both fit all 22mm watchbands. Just adding an additional design to our customers other than the color option. The manufacturing process for M225 are more complicated and it took longer time and cost for production and that is the only reason why it was price a little higher compared to M180. You may refer to attached photo for a clearer comparison.
We love both M180 & M225. It is base on personal preference on which to select. As personally i feel that M180 suits Zulu & Nato strap best while M225 match metal straps and leather perfectly. However, these are my personal liking while it is still base on your personal preference in selecting which design to go for.
Or you may check out our fan made video here for a better understanding ;) https://www.youtube.com/watch?v=pT0EcpJ3YlI
More details about SteelConnect M180 & M225 here
Do not hesitate to contact us at firstname.lastname@example.org for more inquire.