I used this online pdf resizer.
Oh dear… 🙁 It very likely messed with the color space to something else during the “resizing”. I just did a test on a PDF file of my own, and it definitely changes colors. 🙁 My original PDF was in CMYK, and the resulting looks like it got converted to RGB. (That’s just a guess, because I’m not sure how to actually check.) See here for a comparison and a bit of an explanation.
So unfortunately, it looks like your “sample” print was made from a “polluted” source, and therefore was not a good reference point for the actual final results.
I am rather surprised to see such a drastic difference though; I’ve never seen results like that from a printer. Did you edit/push the photos pretty heavily in post processing?