No difference. Just don’t use paste that has other medicines in it. (A few of them have stuff for flys or something as well).
is this the bad one?
Gasterophilus intestinalis, also known as horse bot fly, is a species of insect of the family Oestridae, and is found worldwide. The adults, which have a bumblebee-like appearance, are prominently active in the summer. G. intestinalis is primarily a parasite of horses, mules and donkeys.