Flashing, by definition, does no checks. The partition layout needs to be similar enough for it tho fit, but that’s it. Thus the script doing additional sanity checks beforehand.
Do you have reason to believe it is the same? Ensuring you have a recovery path and then testing seems a very sensible suggestion (if you already happen to have one). Buying one and expecting it to work, not so much.
And it has been different for others: GitHub - g7/sailfishx-patcher-f5321: Patcher script that applies the f5321 (Xperia X Compact) compatibility layer on top of official Sailfish X f5121 images
If nothing else, single vs dual sim is a very common cause for different images.