Hello Carl, and thank you for your question and photos. You are correct, this insect is a type of stink bug (alternately, shield bug), and it does not appear to be a brown marmorated. One of the ways you can distinguish other stink bugs from brown marmorateds is by looking at their legs, antennae and shoulders: brown marmorateds have white bands on both their legs and antennae, and their shoulders are rather rounded and blunt, as opposed to being pointed and sharp. There are quite a few different species of stink bugs in our region. Below is a link with more information about them, including clues for identifying the different kinds.

https://extension.umd.edu/resource/common-stink-bugs-mid-atlantic-hemiptera-pentatomidae

I hope this is helpful.

~ Karin