swine cast before a pearl

This thread began with the hypallage above, which juxtaposes "swine" and "pearls".

But I remember the 'obverse' as "casting one's pearls before pigs" [not "swine"].

Which leads me to wonder:

Is there any substantive difference in meaning between the word "pigs" and the word "swine" which would account for the fact that "pigs" [and "hogs"] are people who overindulge themselves [usually with food], whereas "swine" are people who are morally debased, although not necessarily gluttonous or overweight?

Is it simply a matter of 'sound' rather than meaning alone?

For example, would you say that the word "swine" attaches itself more easily to the imagery of a barnyard befouled with excrement than does the word "pig" or "hog"?

Or can it be that "swine" are more deserving of opprobrium than "pigs" and "hogs"?