[Varstahl]

I don't know the specifics of the things you're talking about, but as far as PrimeVideo artwork go, it's usually:

• Movie poster
  
• Fanart (sometimes)
  

or, for tv series:

• Poster, if available
  
• Horizontal series banner
  
• Season banner for each episode
  
• Episode cover (sometimes)
  
• Episode thumbnail (sometimes)
  

Again, without knowing what you're doing or what data is returned, I can't really know. The data is not even the same geographically, there's a lot of variance. One thing I noticed actually, after some recent changes in their servers, is that they no longer have pre-rendered season posters for example, they have a clear background and a transparent logo they overlay on top, which doesn't happen for movies, obviously. That might be the reason why.