- both are symbiotic cultures of bacteria and yeasts (known in some circles as "beasts")
- both are "fed" in order to multiply and grow, before being divided when you want to use them
- After division, part of the culture is used to make the product, either ginger beer or bread, and part is kept and fed again
- There is only one ginger beer plant, as far as I know, but there are many sourdough cultures and each one is different
- You can only get an authentic ginger beer plant from someone who already has one, but you can make a sourdough starter from scratch
So far it's looking a wee bit frothy, but it's not very lively. I need to feed it again today, and tomorrow I can use it to make bread. I'm also waiting for an established starter to arrive in the post, so I can compare it with my home-made version.