As far as I can tell, "nest" is for whatever easy place the yukkuris are living in, while "bedding" refers specifically for something for them to sleep in.
What Tinweasel said. Bedding is specifically material for the yukkuri to sleep in, while nests are where they live, generally. E.g. boxes, nest holes, etc. Bedding can be part of a nest.
I don't think yukkuri_nest_hole is too close; it refers to any hole that a yukkuri lives in. Nests, to me, refer originally to bird nest-like structures (which is what started the tag), and then more generally to any bed-like structure larger than a few leaves on the ground.
I've been thinking that yukkuri nest hole is a subclass of a nest, which to me is any place yukkuris are living in, which is quite different to bedding. So it's nest (general) -> yukkuri_nest_hole -> bedding. So it's different in purpose to nest, even if the two overlap. I originally set bedding on several images, afterwards doctorsnake_mkiii began adding the nest tag too.
Yes, the first time i confuse a meaning of beding and the nest. it is very close for me but i think beding will give warmth feeling for family friendly more than nest .It like between the meaning of house and home.
Bedding is an item (used as a sleeping/cushion material) that may be found inside a nest as Three says; not an actual "nest" itself like the comparisons there. Nest is the general tag, used when something is used as a nest by the yukkuris; includes both nest holes and boxes, etc. yukkuri nest hole is a type of nest. I need to go back and retag a lot of the box ones, but I haven't had the chance to do that yet.