I feel like "Dynamic" Is defining "Actions" combined with "Parameters", while "Parametric" is more the constraint parameters.
In AutoCAD, I find that constraints and constraint parameters are less stable than using the actions, especially during block creation. I use actions whenever I can get away with em. And they are quicker and easier. I can, however, make almost any block with either actions or constraints exclusively (some exceptions of course). I only recently learned that actions could be "scaled"; previously I had to use constrain parameters if I wanted something to "stretch" by a factor. I can create dynamic blocks much faster using the actions too, along with being more stable. Is it worth paying extra $100's of dollars for each year? Probably not, especially since BricsCAD says you can import blocks made in AutoCAD into BricsCAD. One could utilize the monthly subscription and just spend one month per year making/editing blocks. Then back to BricsCAD.
Learnt a ton... but only so much time in a day. I'm still scared to commit to something 100%. If I do maybe I ought to post my review/experience.