Whats the difference between preloadrs

hey ppl!

whats the difference between thumbnail preloadrs & a basic one?

i’m working on an XML gallery & i have a prelodr for the container…where the large image loads…can i use the same one for thumbs?

i can’t find anything on thumbnails preloadrs…other than senoculars dynamic mini preloadrs…but since i’m using XML …its getting complicated.
:puzzle:

any1?