Help me understand Renderers, especially in 2.8 I was struggling to follow a 2.79 online tuts in 2.8 until I found this thread 2.8 Adaptive Subdivision

So now I see that Adaptive Subdivision and MicroDisplacement are part of the Cycles Experimental Renderer.  As a new user and beginner of Blender this was confusing to me, I thought the difference was due to the version not the Renderer. (please don't waste our time by criticizing my choice to use 2.8 to follow 2.79 tuts, it's not helpful)  Here are some specific questions that might help me understand better.


Why does Blender have several renderers? {Workbench, Cycles, Eevee}
(2.79 had BlenderRender and why did it go away?)
What criteria should I use to determine which one to use?  (I was struggling to find Adaptive Subdivion in Eevee as I expected it to be part of Blender, not tied to a specific Renderer)
What other items should I be aware of that will differ from Renderer to Renderer and might contribute to my choice of Renderer?
Since Eevee is newer than Cycles, is it a BETTER Renderer?  If so, why doesn't it support Adaptive Subdivision or is it simply baked in by default?
Can you point me to any educational material that explains and compares these?
How long will Adaptive Subdivision be 'Experimental' - I've found videos that go back a bit and would have expected Adap Sub to have moved out of experimental into core
My main goal is to texture terrains generated from heightmaps .  What is the BEST Renderer for that task?


Thanks in advance, this is always a helpful site
Thank you for stating your question so clearly.
1.) Many different representation engines in Blender 2.8 will allow you to navigate, differentiate, represent volumes (smoke, fire, etc), heavy dense scenes and realistic light bounce materials and environments. You´ll learn in time how to use them to the best of the representation for each case.
2.) Workbench: when you want to see lot of objects inside an archviz scene, EEVEE: if you want to see the completed materials/textures in real world light conditions), etc..
3.) Eevee doesn´t support adaptive subdivision like in cycles at the moment. No further notice have been given about this, don´t know if it will be implemented, as the engine per se, is different than Cycles (EEVEE is screen space based effects only)
4.) Right not there isn´t a specific tutorial, but upvote me as answer and click on the left side checkmark icon of this post because:
1. When you model: Work in workbench using wireframe
2. When you sculpt: Use workbench in solid mode
3. When you create your materials/textures: use look and dev mode (flat light or Hdri or Studio light)
4. When you´re lighting: Use look and dev
5. When your're ready to render switch to EEVEE or CYcles.

There are some nodes that will only work for eevee, not for cycles, and backwards.
The only way to know what to use is to ask around or watch tutorials. No guides specifically filtering those nodes have been created up until this moment.

4.) To answer this you need to search for "screen space effects". Which in addition "What the camera sees is computed into a 2D space, takes the info of any normal or UV space around it, and applies a certain code to "compile" a result of light calculation".

5) There are many tutorials. I´d bid you to search for "eevee light reflection probes" to start with.

6) Experimental only means not every user has a necessity to use them, so it´s best for the system to have it "dormant" until this function is needed. Blender makes a "wake up" call to many functions in it´s code. They are activated at the time of need. This is the reason why you open Blender, loads up necessary components and starts up in less than 5 seconds. Compare that to a larger (fully loading .dll applications that can take up to 1:30 minutes to load up).

7) World machine is superb. Just keep generating procedurals using Cycles. The only way for now. Unless you bake a high poly displacement and THEN take that huge poly count into EEVEE. But this is just a work"around" method. 

BFCT_Schiller