I don’t think the version is different at all. Just the delivery system and the way it is encapsulated/suspended. Humans and small animals can get a pill. Farm animals get a paste and possibly a subcutaneous injection (not 100% sure on that). Otherwise, ivermectin is ivermectin - like acetaminophen is acetaminophen whether gel cap, capsule, tablet, or children’s flavored liquid.
1.87% ivermectin is the same medicine whether designed for horses or people.
It’s packaged differently, but it’s the same medicine. Just like fishmox is the same antibiotic used for humans.