Is the words occurred and happen have the same meaning?

Answer 1

Yes, you can say

"It happened at this time"

or

"It occurred at this time"

both would mean the same thing.

Answer 2

Generally, "occurred" and "happen" have similar meanings, both referring to something that took place or transpired. However, "occurred" tends to be a bit more formal or precise in its usage, while "happen" is more commonly used in everyday language.