@Mary Tillios thank you, to clarify, we're using just one type of subway tile in one bathroom. I'm debating using it at all because we already have a different type of white subway tile in another bathroom upstairs. I was wondering if it will look like the renovations were done by different homeowners or done at very different times, because the wall tile I have is the super plain, cheap white subway and the one installed in the upstairs bathroom is pricier with a undulated look to it .

It will not look strange. Particularly since one is the master bathroom, and that is typically done in a more upscale mode than other bathrooms anyway.

I think it will look great. Your inspiration pictures are very attractive. No one will notice or care that the master has a different type of subway. It’s probably better that it’s smoother than your master handmade style tile because, being near the mud room, it’s good to be smoother and easier to clean.

It will look fine. Realistically how many people are using both the master bath and guest powder room? And of those do you really think they would notice the difference in subway tile?

If you like the white subway tile then absolutely go with that. Each bathroom is it's own area. IMO it would only be detrimental to use different white subway tiles if they were in the same area.

Matching is boring. Subtle differences are fun if you like them.