I don't think the two are mutually exclusive. For example, one can express their hatred of a ethnic minority group in a strong and confident way such that people take notice, which by your definitions could qualify as assertive and aggressive.
Why are you so scared of this topic? You are trying so, so very hard to make assertive = aggressive. Maybe you should reflect a little bit on why you are trying to force a narrative so hard? Perhaps this is a touchy spot for you.