Easily-confused!
If your specimen is:and has stems/​leaves ar­ranged:and the leaves have/are:and the bark is/has:and the twigs:and the fruit (if present):then you have:
no more than waist-high (<1 m) (<3 ft) ╟ alternate ▲▲ teeth no hair lookalike alderleaf buckthorn  Rhamnus alnifolia.
a tree ▲▲ teeth, visible within arm's length dark, lots of light-colored lenticels

if mature, looks covered with burnt potato chips/​crisps
are small, black, taste like 🍒︎ cherry even if sour lookalike ◼︎🍒︎ black cherry  Prunus serotina.
___ smooth margins or
▴▴▴▴ very small teeth (use 🔎︎ hand-lens)
dark, lots of light-colored lenticels no terminal thorn;
hairy
lookalike glossy buckthorn  Frangula alnus.
___ smooth margins,
taper at both ends, and
pass the dogwood leaf test
no con­spic­u­ous lenticels nor strong colors this plant (2 species), please continue below …
sub-opposite ▴▴▴ small teeth (can use 👀︎ naked eyes) dark, lots of light-colored lenticels

inner bark=​orange (scrape with 🔪︎ knife)
often have a terminal thorn are small, black, taste disgusting after a few seconds—spit it out lookalike common buckthorn  Rhamnus cathartica.
╫ opposite ___ smooth margins,
taper at both ends, and
pass the dogwood leaf test
no con­spic­u­ous lenticels nor strong colors this plant (all-but-2 species), please continue below …

Stop on this taxon with verify with 🔍︎ images, learn more;  or continue identification …

Learn more about dogwood genus Cornus (Cornus spp.)

🔍︎ 🔍︎ images Discover Life Encyclopedia of Life Michigan Flora Minnesota Wildflowers Flora of North America NRCS PLANTS db Wikipedia