Darwin's book came out in 1859, but we didn't learn about DNA until 1948. So, the science has definitely moved on, and the definitions did too. To make it worse, some dictionaries have terrible definitions. I'll try to do better. The first word we need is observation .
Observations are the raw evidence.
They are directly known, and usually not open to debate. A fact can be an observation, but it can also be something that we know indirectly. For example, ocean tides are an observation, and it is a fact that the Moon and Sun cause the tides. Gravity causing the tides has been a fact for centuries. But notice that all scientific knowledge is by definition tentative and provisional, so a fact that is not an observation does have some faint chance of being overturned someday.