In terms of normal meaning, there isn't a difference. However, the two can be interpreted as having different grammatical nuances, and they aren't completely interchangeable.
When I hear not educated (and it may be different for others), it conveys to me a sense of having received no education in the past. But when I hear uneducated it seems to be more ...
But if I am not sure which prefix I have to use with, for example,
"understand" can I just put "not" before it to have the same sense?
Regarding misunderstood vs not understand, I would take it that misunderstood means the listener thought that they understood what was said, but had perhaps acted slightly differently based on their interpretation.
On the ...
What does "unless" mean in this dialogue?
The meaning follows the dictionary definition:
- except under the circumstances that:
"I'll be there at nine, unless the train is late."
B: You just said you wanted to help me. Oh, unless you weren't being serious,
B: You just said ...
1) I did not it
No, this expression is not generally used.
2) I did not do it
Number 2 is correct English
3) Not I did it (but he).
Number 3 is not generally used.
The distinction that you want to make between 1, 2 and 3 are made by stress
I didn't do that. (But he did)
I didn't do that. (But I did this)
Similarly, the question forms could ...