To be fair, Vietnam was a war being waged directly by the US. That’s not to say that I think the protests will be ineffective; if they weren’t having some effect then we wouldn’t be hearing about them. However, the situation is somewhat different from the Vietnam war. That’s why (if I understand correctly) they’re mainly protesting to end US involvement as opposed to trying to make Israel stop. Ending US involvement will probably result in Israel stopping, but there’s no guarantee and so the main idea is to make sure the US is not complicit. At least that’s my understanding of the nuance when it comes to the situation.