A musical work can have many different names in different languages. Knowing the standardized form of the name, called the uniform title, can help retrieve relevant scores and recordings.
To retrieve more relevant results for a specific title:
You may need to search in a few different ways, particularly if you are trying to find multiple editions, performances, etc. of the same work.
Form titles use the common genre names such as Sonatas, Masses, Quartets, etc. They list the genre, the medium, the distinctive number if one exists, the key, and then any extra information.
This is a record for a score of Beethoven's Moonlight Sonata, which has a form title. Searching with the title of "Sonatas, piano, no. 14, op. 27, no.2, C# minor" (and Beethoven as the author/creator) will retrieve recordings and scores that specifically list this piece, but will not retrieve records of collected works of all Beethoven's sonatas.
Collective titles are used for editions of complete works or for collections of works in a specific form (e.g., all sonatas), by a single composer. If we have a complete works edition of a given composer, you'll find it listed under "Works."
Searching with the title "Sonatas, piano" (and Beethoven as the author/creator) will retrieve scores and recordings that have all of Beethoven's piano sonatas as well as publications with individual piano sonatas.
Distinctive titles are for works that have unique names. The distinctive title lists the name in its original language and helps to retrieve all versions of that work even if the name has been translated.
For example, the distinctive title for Stravinsky's Firebird by Stravinsky is Zhar-ptitsa.