Verbal Expert Topic That “-ing” word probably isn’t a verb

Hello GMATNinja

I have a question, which needs to be resolved as the concept behind it is very confusing.
You gave us this example :
Walking through the forest, the pig happily hunted for truffles.

and then also mentioned that :
Notice that the "-ing" modifier must "make sense" with the subject, too: it's reasonable to say that the pig is capable of walking through the forest.

Until this point, I was good, but then there is a link that you have attached above and that link is about how verb-ing and verb-ed words can be parallel. Quoting the same;

The sentence discussed in that post is as follows -

In this question that has been discussed by egmat, Payal says that the portion underlined are the two characteristics of local time, but from what you explained above, I thought that the verb-ed modifier (determined) and the verb-ing modifier (differing) are modifying the "GROWTH of the railroads" and that didn't make sense to me and hence I crossed-out options D and E.

I am not able to understand, with that construction, that how do we determine whether those modifiers are modifying the subject of the sentence (Growth) or the noun (local times) that they immediately follow. If the latter one is correct, then is it not contradicting what you explained in the post above?

In anticipation of your explanation. Kind Regards!
Thanks in advance.