I've been with DooM, DUKE3D and BLOOD for several years now

I'm just investigating some concepts behind this two engines.
This is what I found out:
BOTH are 2.5D sector based engines, support slopes and got OpenGL, HiRes texture and MD2 support.
ZDOOM
- uses BSP tree to store sector/level information, thus levels are static
- moving map parts are possible only by using zdoom/hexen polyobj hack and aren't real sectors
- doesn't have "native" editor, mapper is unable to preview level realtime
- doesn't support sector over sector mapping
- zdoom has acquired powerfull ACS sripting language and sector capabilities
BUILD
- uses some diffren't algorithm for visibility calculation (which one) ?
- map is completely dynamic, any sector can be moved
- has "native" editor with online preview
- supports sector over sector scheme when certain conditions are met
- has quite obscure sripting system
My question is mainly, can you tell my what algorithm current OpenGL BUILD incarnation uses?
My second question is wheteher there are BUILD technology parts at charge in ZDOOM's core?
There has been screenshot with BLOOD level on zdoom site sometime, so I assume that current ZDOOM converts actual native DOOM maps into some intermediate form in memory much more similar to BUILD one's and uses BUILD's rendering techniques.
My third question is, are there any other differences?
Thank you