If I weigh an elephant in India, Africa, and the United States, I expect that same elephant to have the same weight in each place.
Who cares? In the beginning it was the merchants who cared. Elephant sellers and buyers wanted to how much pachyderm they were exchanging for a fixed amount of gold. The men they relied on to tell them if the weights and measures were accurate were often scientists. And this principle of repeatable observation became known as the scientific method. When applying the scientific method to the weight of the elephant, we do not seek to discover anything. We would like the weight of the elephant to be the same no matter where we are on the surface of earth.
However, the weight of the elephant will not be exactly the same everywhere on the earth. It was up to science to discover why. It has been discovered, for instance, that the earth is not perfectly spherical, but rather an oblate spheroid. Also, some parts of the earth are denser than others. If the instruments to weigh the elephant, the scales and such, are made of metal or are electronically based, then they might be affected by localized variations in the magnetic field.
Discovery is usually used when we talk about finding something new. Something we did not know before. Often,scientific discoveries are made by making scientific observations. Observations need to be repeatable, precise, accurate and relevant. Observing that the elephant is gray has no bearing on its weight even if we are very precise about the angstroms of visible light that produce that particular shade of gray.
Almost any scientific observation which is repeated often enough will result in a new discovery. One reason why this is so is that the scientific instruments we use to measure things become more accurate as time goes on. The more accurate the measurement, the more likely you are to make a discovery that does not jibe with conventional scientific theory.
For most scientists, most of the time, making a new discovery is difficult. There are so many scientists probing the universe with so many scientific instruments that much of the low hanging fruit was discovered long ago. The realms of science wherein new discoveries are frequently made often involve probing remote regions of space or the ocean. The more remote something is the more expensive it is to reach it.