Very similar...apparently they can be distinguished by their flowers. The petals of P. padus are larger than P. virginiana and the petals are also longer than the stamens. In a nutshell, petal to stamen length ratio is larger than P. virginiana.

Mayday has smaller often more bitter fruits and yes, fresh chokecherries can really give one that back of the throat "choking" sensation, but occassionally I come across a bush that doesn't. Chokecherry jelly is RICHLY flavored and delicious and completely loses the choke factor, it's one of my favoite of all jellies!

Some choke less chokecherries I found growing down the road and moved them to my yard.

From eFloras Flora of North America:

Petals 2–5(–7) mm; sepals 0.7–1.4 mm (lengths equal to widths); stones ± smooth.

7 Prunus virginiana

+ Petals (5–)6–9 mm; sepals 1.2–2 mm (lengths greater than widths); stones rugulose.

8 Prunus padus

Thank you all, no flowers at this time, :), We have decided based on taste that these in question must be chokecherries. I bought my bush labeled as a Mayday, in comparison they are much more astringent than the bush in question. I can easily eat the berries from the other tree.

Oddly, I have a green leaf Mayday and a burgundy leaf, between them the burgundy leaf has larger berries and is more repugnant than the greenleaf.

Presumably when you type "Mayday" you are talking about P. padus.

Well, if the tag was still there and I knew for sure what it was the post would be moot. Thank you for your information about the flower petals, next spring when in bloom I will compare the two trees in question.