Well, they can be distinguished, but they often aren’t in everyday speech. I get confused sometimes too. So are you saying that “culture” is a collective noun with many aspects? You do say “cultures” too, don’t you?
Yes, but then we’re speaking of different groups, like French culture, Tibetan culture, or Korean culture.
So we should teach our students that sometimes the word “วัฒนธรรม” can be used in the same way as “culture” but sometimes it can’t. How would they know?
Sadly, there are no shortcuts or simple rules. But one should never call a single behavior or belief a “culture.” It’s a part of a culture. Correct usage takes a long time to learn, like I’m finding out learning your language. Maybe it never ends, since usage is changing all the time.
Just like cultures, changing all the time.