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:
a tree ╫ opposite ___ smooth margins,
taper at both ends, and
pass the dogwood leaf test
no conspicuous lenticels nor strong colors lookalike all-but-2 species of dogwood  genus Cornus.
sub-opposite ▴▴▴ small teeth (can use 👀︎ naked eyes) dark, lots of light-colored lenticels

inner bark=​orange (scrape outer bark with 🔪︎ knife)
often have a terminal thorn are small, black, taste disgusting after a few seconds — spit it out lookalike common buckthorn  Rhamnus cathartica.
╟ alternate ___ smooth margins,
taper at both ends, and
pass the dogwood leaf test
no conspicuous lenticels nor strong colors lookalike 2 species of dogwood  genus Cornus.
___ smooth margins or
▴▴▴▴ very small teeth (use 🔎︎ hand-lens)
dark, lots of light-colored lenticels no terminal thorn;
hairy
lookalike glossy buckthorn  Frangula alnus.
▲▲ 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 this plant, please continue below …
no more than waist-high (<1 m) (<3 ft) ▲▲ teeth no hair lookalike alderleaf buckthorn  Rhamnus alnifolia.

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Learn more about ◼︎🍒︎ black cherry Prunus serotina

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