What is the difference between these two libraries? Are they both normal Kontakt libraries or are there separate versions for Win and Mac? Are they both really over 600 gigs??

 

They are two orchestral libraries recorded with different players at different places. In short, they sound different and yes, they are pretty big (Spitfire has a tendency of quantity over quality). If you are willing to put time into learning them, both will work the same, they just have different characters and maybe different articulations for the niche stuff. I particularly moved on from Spitfire, there are better libraries around when it comes to strings.

 

Thanks for the info @shinjiya , first time hearing Spitfire is lower quality, I thought their Symphony library is top tier modern orchestra as far as virtual instruments go. Is there a better modern symphony orchestra library? What would you recommend?