Difference between an oven tray and shelf

[Nameinspirationneeded]

I should know this. I have a ready meal and it says put direct on oven shelf. I normally use a tray. Is there a big difference? Tray may be easier for me to lift out but just wondering.

Is it a pizza? If not use a tray but heat the tray first

I don’t think the ready meal will know the difference tbh!

That’s what I thought, maybe get hotter on shelf as the meal is in a metal tray. I’ll use the tray, my oven shelves are a pain to move.