From todays Medcram video.
Pages 20 and 22 shows the mutations and how they extend.
Also, the blue represents (L type) the more serious strain). The red (S strain) represents the milder one.
Sorry for the crazy pdf link.
You can find the info by clicking on pdf and going to pages 20 & 22
https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463