A lie is typically a statement or story that is provably false.
Disinformation, on the other hand, has a more precise meaning - it is a deliberate pattern of lies, exaggerations, innuendo, unsupported opinions and half-truths, usually intended to change public opinion. The difference between disinformation and propaganda usually comes down to whether or not it is a government vs. non-government entity that is spreading the disinformation campaign.
The reason for the distinction is primarily because we have taken as "ground truth" the statement that all politicians lie, something that in practice is usually not the case, primarily because it is fairly easy to rebut such lies publicly. Trump came to power initially as someone who wasn't a politician, and that as a consequence you could trust him. This was only feasible because the media generally didn't call him out on his lies early on and normalized them, which in turn corrupted many of these media because normalization brought novelty and ratings. We have reached the point, however, where many media outlets are no longer trusted because they have ceased even trying to deliver truth, and instead have become simply conduits for one very narrow viewpoint.
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