Usage of emojis as compared to stickers

The rise and uptake of IM applications has created some interesting ways for users to communicate with each other, with the emergence/popularity of emojis (which could be said to be an evolution of the emoticons) and stickers being the two that comes to mind for me.

However, since I am not a very active user of social media platforms, I am curious as to what the difference between emojis and stickers as they are used in IM applications. The two things that I notices are:

  1. Stickers will incorporate words on a regular basis, whereas emjois tend to be purely symbolic
  2. Stickers tend to be larger in size and more complex in design (not necessarily true), whereas emoji have a smaller footprint and are simpler in design (although they appear to be getting more complex)

What other differences have people noticed?