Orchestral
This category is generally called orchestral pop, or sometimes "symphonic rock" when it applies specifically to rock and prog artists (AllMusic, n.d.-v). It refers to music originally written by pop or rock artists that gets arranged and performed by a full symphonic orchestra, rather than the artists' own recordings (AllMusic, n.d.-v). Think of it as a cover version at the level of an entire ensemble. Instead of one new artist reinterpreting a song, a whole orchestra reinterprets it, trading guitars and drum kits for strings, brass, and woodwinds.
This trend has deep roots with exactly the artists you're collecting. Following the Beatles' 1967 album Sgt. Pepper's Lonely Hearts Club Band, which leaned heavily on classical touches, the Moody Blues used a full symphony orchestra to record Days of Future Passed later that year, an album generally considered the first true symphonic rock record (Top 10 Orchestral Rock Albums, n.d.). A real wave of these projects followed in 1977, when the London Symphony Orchestra launched a "Classic Rock" album series performing orchestral versions of hit songs by mainstream rock acts (Symphony to Synths, n.d.).
Prog rock bands in particular became frequent subjects, since the genre already leaned toward elaborate, orchestra-adjacent arrangements. Former Jethro Tull member Dee Palmer, previously credited as David Palmer, became a key figure here starting in the 1980s, arranging full orchestral tribute albums for Jethro Tull, Pink Floyd, Genesis, and Yes (Dee Palmer, n.d.). Some specific titles line up directly with your collection: Jethro Tull recorded A Classic Case with the London Symphony Orchestra in 1985, Genesis got the London Symphony Orchestra treatment on We Know What We Like in 1987, and Pink Floyd has been arranged multiple times, including Palmer's Objects of Fantasy and the separately arranged Us and Them: Symphonic Pink Floyd, performed by the London Philharmonic Orchestra in 1995 (Dee Palmer, n.d.; Us and Them: Symphonic Pink Floyd, n.d.). The Beatles have received this treatment repeatedly as well, from early orchestral tribute records straight through to newer projects like the Antwerp Philharmonic's 2024 Beatles tribute album (Another Seven Symphonies, n.d.).
Sources:
AllMusic. (n.d.-v). Orchestral/easy listening music style overview. https://www.allmusic.com/style/orchestral-easy-listening-ma0000002765
Dee Palmer. (n.d.). In Wikipedia. https://en.wikipedia.org/wiki/Dee_Palmer
Top 10 Orchestral Rock Albums. (n.d.). In Ultimate Classic Rock. https://ultimateclassicrock.com/orchestral-rock-albums/
Symphony to Synths. (n.d.). In DPRP.net. https://www.dprp.net/features/2017/symphony-to-synths-part-7
Us and Them: Symphonic Pink Floyd. (n.d.). In Wikipedia. https://en.wikipedia.org/wiki/Us_and_Them:_Symphonic_Pink_Floyd