The reason you are seeing a difference in behavior from "Search" (or "Advanced Search") at the dataverse level vs. "Find" at the dataset level is that the former is powered by Solr, which (as a search engine) is friendlier and more forgiving about user input and the latter is powered by a SQL query*, which is less forgiving.
(I didn't actually type the quotes above.)
However, the SQL query doesn't find the file/dataset if the hyphen is missing. (That server is running 4.5, by the way.)
Perhaps the takeaway or workaround is to be aware that if you're having trouble finding a file at the dataset level, you can always back up to the dataverse level and see if you have better luck searching from there.
I suspect that most users would prefer the more forgiving search behavior (you can always make it more strict by putting quotes around your query) and there's an existing issue called "Use Solr for file listing on dataset page" at https://github.com/IQSS/dataverse/issues/2455
but it's a significant amount of work. Anyway, you're welcome to open a more targeted GitHub issue if you'd like to capture the behavior above as a bug.
I hope this helps!
* I think in the code the method is called "findFileMetadataByDatasetVersionIdLabelSearchTerm" which is using "LIKE %searchTerm%" syntax.