How do you define Variants?

Weighted trains/unweighted trains

I'm worried I've bitten off more than I can chew here I think I'll mention that 2017/1 is available in both weighted and unweighted, but I'm not sure I want to add a dozen more checkboxes for that, absent better reasons.

In the case of Batman 52 with and without eyeballs as a variant. As the name on the bottom of the trains are different for the one with eyeballs and with the one without.

Do you know what each version's name is? I probably saw the difference a long time ago but I've forgotten and I'm hoping it will take you less time to just look at yours than it would take me to search the whole thread here If it's not easy for you, I'll go looking.

I guess it really depends if variants are something you want or even care about. I personally enjoy the challenge of finding the differences. I still need to figure out if I have the Skarloey variant or not..

What I'm trying to balance is how to provide some value for the collectors like you who are looking for everything while still making it super-easy for the casual fans who just want to know what they have or find a specific train without getting bogged down in the details. So if you have suggestions on how I can make things easier for you without making it too hard for someone new to Minis to understand what's going on, I'm all ears!

I wouldn't consider factory errors as variants.
A variant is any existing model that is released with any different feature, such as face, sticker design, paint color (or lack of), effect, appointment, function, language, etc...it could even be as subtle as a different styled font.

So how do you tell the difference between an error and a variant? Is it just knowing the line pretty well and watching how many appear? The Batman-52 eyeballs thing, for example: I had assumed it was an error but between someone else asking for it and mikedaws' note here about distribution, I guess it must be a variant.