alt Hacker NewsIn the phonetic alphabet it's /e:/ vs. /ei/ and /o:/ vs. /ou/.
If you're an English speaker, you can be forgiven for a very stereotypical trait of the English accent. English speakers have a real hard time with the /e/ or /e:/ sounds as well as the /o/ and /o:/ sounds. Most English dialects don't have either a monophthong /e/ or /o/. Both the long and short tend to get heard as /eɪ/ and /oʊ/.
French enchanté /ɑ̃ ʃɑ̃ te/ is heard and borrowed as /ɑn.ʃɑn.teɪ/. German gehen /ge:n/ is heard as "gain" /geɪn/. And Japanese /o:/ and /ou/ both get heard as /oʊ/.
It's arguably a minimal pair in Japanese: 負う /ou/ (to carry), 王 /o:/ (king).
負う and 王 are both hepburn-romanized as ou though. 方 and 頬 (hou vs hoo) is a better example. I don't really think native speakers still distinguish these.
Feel free to try listening yourself though:
頬, note that it has multiple pronunciations but we only care about hoo: https://forvo.com/word/%E9%A0%AC/#ja
方 https://forvo.com/word/%E6%96%B9%E3%80%80%EF%BC%88%E3%81%BB%...
In some cases though there is still a clear difference in pronunciation for most speakers, ex 塔 vs 遠