IgnoreDecorativeDifferences would basically mean that any block could be replaced with any block wit identical properties without causing an error overlay or a problem in verification,, for instance, a schematic built out of iron blocks could be built out of concrete or anything else without causing an error. Probably just anything that shares all properties except blast resistance, could be done as a blacklist.

And IgnoreDecorativeDirectionDifferences just ignore the placement direction for glazed terracotta and other blocks that can have different directions but don't matter.

There is a generic system planned for "valid block substitutes". It won't be a hard coded system for just certain properties or block types, but instead the idea is that the user can define lists of blocks or block states or block tags that are valid substitutes for a given block type or specific block state.