Considering Queen’s live performances deliberately favoured the visual/theatrical aspect just as much as the strictly musical one, it’s understandable that they weren’t trying to recreate the studio versions of their material, leading to noticeable differences in the instruments used and the way they were amplified:
Generally, amplifiers and mics would feed the Public Address System (aka PA or Tannoy), which would then direct the sound to loudspeakers strategically placed for the entire audience to hear properly and to a fold back so the performers would hear what they were doing either via monitors or canalphones. Technology marches on, of course, so what Queen had relied on back in 1970 was completely different to what they used in 2020 just before the pandemic hit.