Fact is the opposite of truth.
What I mean is this: Facts are objective, truth is subjective.
Example: Fact--the Earth is shaped as an oblate sphere. Truth--WWI is largely the result of the alliance system.
One is objectively the case. It cannot be argued against. It is not an opinion, but something rooted in observation. We can measure it, we can observe it from a distance.
The other is an opinion which is widely accepted. It's an idea. It is an interpretation. It cannot be measured physically, only tested against other ideas. Truth can be false.
This is why when you are a witness in a trial, you swear to tell the truth and not to be factual.