Up here in NW PA we enjoy the black-capped chickadee. It's very similar to the Carolina Chickadee but has more white on the wings as described here
as an inverted white hockey stick. It's bib margin is generally less uniform than that of the Carolina Chickadee as well. The black-capped is also larger with a relatively longer tail, but without a side-by-side comparison that would be hard to distinguish.

