Despite the initial silliness of the question, they are very different. Currently Null bulges are included in the null tag. The rest of the tag regards characters that lack genitals, while a null bulge is most often not a lack of genitals, but instead a permanent encasing of them, so despite sharing the term null, they're very different and null bulge images stick out like a sore thumb in the rest of the null tag. I think it will be better to split the tags off from eachother once and for all and define null bulges as not a lack of genitals, but encased genitals or a different kind of genitals of their own.