Are truthers and birthers equivalent? Yes, in most senses, but no in one other.
Birtherism is a misguided theory about Obama which, even if true, does not allege that he is partially or wholly responsible for the murder of thousands of Americans. In fact, if the birthers were correct, it wouldn’t even be Obama’s fault.
That’s why the truthers are, in fact, far more unhinged than the birthers.