1. if it has figures, mud men, etc. it is Penjing.
2. if it has a lot of landscaping, streams, stones, etc. it is Penjing.
3. if it has a variety of species of different types such as tall trees
and shorter shrub like plants it is Penjing.

I beg to differ. Only #1 is true, in the classic sense. Some of us use
figurines in what would otherwise be called saikei.
If you read Kawamoto's book on saikei, you will find that #2 and #3 are
definitely not true. I suggest you go back and read Korashoff. She goes into
detail on the difference between Chinese & Japanese styles. At any rate,
nowadays the distinction is quite blurred.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)