I grew up in a Hydrox house. If I eat a cookie these days, it’s definitely NOT a supermarket “sandwich creme,” so I have no idea what Oreos taste like now.
My impression, back in the day, was that Hydrox was sweeter and more of a “milk chocolate” flavor. Oreos were more bitter and “dark choclatey.”
I tried to find a page detailing the Nice! Original Sandwich Crème Cookies that I get at Walgreens, but the only thing I could find is a picture of the package and a list of why I shouldn’t be eating them! But, aside from that precaution, I enjoy them regularly as opposed to Oreo or Hydrox.