A question about tansy vs ragwort

[Flunked]

I've been googling but I'm too tired and, honestly, too thick to understand what I'm reading. Trying to help a friend out as she is also confused.

There are two plants that share similar names, tansy and tansy-ragwort.

Tansy is Tanacetum vulgare. Tansy-ragwort is Jacobaea vulgaris (synonym Senecio jacobaea)

She has always thought that tansy is not really toxic and tansy-ragwort is very toxic and dangerous.

The horses always avoid tansy (Tanacetum vulgare) but the goats just hoover it up. She will generally pull it if she finds it though. Always pulls tansy-ragwort (Jacobaea vulgaris) of course.

So can anyone help clear it up for us?

I was under the impression that tansy (Tanacetum vulgare) is a lot less toxic than ragwort (Jacobaea vulgaris) and I think young plants can be of natural benefit in the fight against worms. I am not sure I would put my horse in a field where the tansy has taken over, but a few small plants are probably not an issue. I don't think horses will eat flowering tansy as it is very bitter but I guess it is not desirable in hay.