Believe it or not, the two lower pictures above show the same plant in bloom, in bloom in different years when the growing conditions during peony season were very different. I'm sure many an armchair botanist might make them different species.
The top photo shows the new growth emerging bud-first from the ground. With this one you know where you stand bud-wise as soon as the new growth appears. This plant typically produces one big flower per stem. When the flowers first open and the dome of stamens is fresh it's a very beautiful sight.
This plant sets abundant viable seed.