Hey there @Vicktorious09, those are good questions. And you pretty much hit it on the nose. Wall/floor covers can be moved around like furniture, so they'd be part of a furniture set (along with all the stuff you mentioned like lamps, tables and so on). Wall/floor skins are patterns that cover your whole wall/floor when placed. So Cherche means you can either submit a furniture set which includes wall/floor covers, or a wall + floor skin set. The second option may be easier for some since it only requires designing 2 items -- although a furniture set could be more fun since you can get more creative and design as many decorations as you want. It's up to you!

Hopefully this answers your questions, but please let us know if you're unsure about anything else!