Your small one is a Mini, your 36" is not a Mini, since he is over 34".
Do you have any history on them? This might tell you what their parents have achieved.
The bigger one is still classed as a mini, just a cat B mini horse. Ive got a registered cat B mini horse who is 38", that's the height limit for them, so heaven help us if she gets any bigger lol.
I do inhand jumping with my one and broke her to ride, although I am a bit big for her, but she is stocky, so while it if safe for me to get on her, i only do so at a walk, and for only a few minutes to make sure she's not going to misbehave for younger children. (she never does though she's an angel)
She also knows how to bow, and back up, she can jump from a stand still, I've taken her to a school gala for pony rides (for small children of course, we had a bigger pony there for bigger children) and we dress her up etc, take her swimming in the river and everything. She would sleep in my bed if she could lol.
^ mind you I dont jump her this high very often, maybe once a month.
mostly its around this height...
she's broken to ride...
and her going into a bow...
She also knows the "smile" trick