The main thing that Tudor is known for is being the sister company of Rolex making watches using, effectively, Rolex cases and parts but using a generic ETA movement rather than a Rolex in-house movement. As a consequence, their watches enjoy the Rolex 'utilitarian' build quality but are typically much cheaper than the equivalent Rolex.
In terms of horological significance, their Submariners are particularly sought after amongst collectors given that they were, in years past, the standard issue to the French navy
https://bulangandsons.com/tudor-and-the-french-navy-a-quarter-of-a-century-of-collaboration/
It is a shame more people don't know about Tudor, in part due to the fact that their ADs operated out of very few countries, for example there were no Tudor ADs in the UK or in the US (although apparently those in the know could always go to a Rolex AD and order these watches). Today, they are re-emerging due to a push to establish more ADs around the world (often next door to or in the same showroom as Rolex) and perhaps more pertinently, with the release of the Heritage Black Bay and the Pelagos in particular, by making very desirable watches in their own right at very decent prices.