These words aren't the same! They have different meanings, different spellings and different pronunciations.
The difference in pronunciation between "hall" and "hole" lies in the vowel.
"Hall" has a single vowel in it. The vowel is /ɔː/. The colon (":") means that the vowel is long. And "ɔ" means which vowel it is: the open-mid back rounded vowel. What does this name mean?
- "Open-mid" means that your tongue is quite far from the roof of your mouth.
- "Back" means that you should place your tongue as far back in your mouth as you can.
- "Rounded" means that you should round your lips when you utter this sound.
Finally,
here's a sample.
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The vowel in "hole" is different. It's not even one vowel! It's a so-called diphthong, which means that the sound starts with one vowel and ends with another. Unfortunately, which vowels they are depends on the accent you speak.
In British English, the diphthong is /əʊ/ (but not in all accents).
In American English, the diphthong is /oʊ/.
Even though they're different, they're still very similar.