What is the difference between Botox, Xeomin, and Coretox?

I get Botox injections occasionally on my forehead and between my eyebrows. I don't remember what type of Botox I received previously, so when I went for a consultation this time, I asked about concerns regarding resistance. The clinic told me they have both Coretox and Xeomin available. I plan to choose one of the two for my next visit; while the imported Xeomin is more expensive, are the effects similar? I would like to know the difference between the two Botox products.