I think both tropes have uncomfortable subtext on a wider level, bimbo more so because it's more common and the trope is typically depicted in a more negative light, though both can be shown positively or negatively. Bimbo is also linked to porn tropes and misogynistic stereotypes in a way that is more pervasive than the himbo trope IMO, which reflects attitudes towards men on a smaller scale and has less of a history. That's my take anyway, what do you think?