I've noticed that emoji and stickers are absolutely not used in the same way.
People often combine multiple emoji to express certain things that can't be expressed with a single emoji (and too difficult to find/create a sticker for).
Stickers are also much less subtle and more in your face, and therefore not appreciated in the same way.
although i’ve noticed mostly human emojis can be used consciously. the others (tree, objects, etc) are suggested when you type a word but almost never selected to replace words in a sentence. So i don’t know who really uses them.
People often combine multiple emoji to express certain things that can't be expressed with a single emoji (and too difficult to find/create a sticker for).
Stickers are also much less subtle and more in your face, and therefore not appreciated in the same way.