I will start off by saying, I just finished my very first semester of nursing school so I am not on the field. But I have perspective: my dad has been an ADN nurse for almost 40 years and my aunt has been a BSN nurse for about 15.
The objective viewpoint from people in the field currently:
Both have to pass NCLEX-RN. Both have to complete a similar number of clinical hours. The ADN degree is more bare-bones and clinical focus, whereas the BSN degree combines a clinical focus with some extraneous courses such as Leadership, Research, and Healthcare Policy/Economics. Moreover, (at least in my area) BSN programs offer at least two semesters of pathophysiology and two of pharmacology while the ADN programs seem to focus solely on pharmacology. My dad says his years of experience has made him a good nurse, better than most if not all bachelor's new grads, but he would have been better prepared at the get-go with a BSN. My aunt says when she was first hired, there was a slight knowledge gap between ADN and BSN new grads but with a few months' experience, it virtually went away.
My personal, humble, not-at-all experienced viewpoint:
My parents never even let me entertain the idea of an ADN because they want all of their children to get at least a bachelor's degree. So BSN was always my only option. I took Microbiology transiently at a community college over the Summer to ease up my schedule and let me say--10x easier than my other science prerequisites that I took at my private, 4-year university (#2 nursing program in my state). Do I find it a bit unfair that the people who got an easier education will have similar job prospects as I do? Absolutely. Do I believe ALL RNs should be required to get a BSN eventually? 100%, and my father and aunt agree. But I know that when I graduate, I will have an edge over ADN grads at least in my area for jobs. I want to end up in the ED--hard for a new grad, but a BSN with a 3.5 vs an ADN with a 4.0--the BSN should win because employers know that BSN programs have much higher standards. Many hospitals in my area won't even hire you with an ADN anymore.
Based on mine and my family members' observations, I believe an ADN nurse can become as competent as a BSN one. It will take more time and I do believe BSN is the superior degree to begin with, but I have just as much respect for experienced ADN nurses as I do for experienced BSN nurses.