When MS releases new builds, like RS1, RS2, now RS3, they mostly mention UI-related features, new Store Apps with new features, etc to the masses (obviously because that is what the masses care about). I could care less for any of that gimmicky bloatware. Generally, if its related to Store/Metro/Flow/UI/AppX, then I consider it bloatware. What about low/mid-level changes/improvements? For example, RS1 updated WDDM to 2.1, which provided HDR support, then RS2 updated WDDM to 2.2, which provided VR support. Another example, in RS1 and earlier editions, renaming folders on MTP devices (like phones) was an annoying experience due a prolonged delay and then in RS2 MS improved on that and there is no delay after renaming. I only realized that on my own, which was further supported by a random article about how removing this delay was part of RS2's new features/updates. Yet another example is the difference between RAM management between RS1 and RS2. RS1 aggregated SVCHOST.exe processes at all times, but in RS2, if you had more than 3.5GB of RAM, you would see a lot more SVCHOST.exe processes in Task Manager because MS decided not to aggregate them in RS2 for the purpose of stability and management (if one fails, others remain, better for troubleshooting). RS2 also comes with FullScreen Optimization enabled, which nobody so far could explain to me, but at least I know that it increases the speed of switching between windowed mode and fullscreen mode in 3D applications/games. THOSE are the kind of differences I care about and right now would like to know more about RS1 vs RS2 vs RS3 on that mid-range technical level because true low-level explanation would leave me puzzled as I would not understand it. I don't even know where to find such information. There are just random articles about random changes and the article about SVCHOST.exe I found by searching Google with "Why many SVCHOST in Creator Update" key words. I looked into RS3 Preview build "Change/Release notes" and nothing worthy to me is ever mentioned. I have no idea if I should even get RS3 because I am clueless about improvements it is going to bring ASIDE from all that bloat and UI stuff. Does anyone even know? Is there even a list?
Multiple svchosts is a design change that contribute to damage control also takes advantage of multi-thread CPUs, in theory it should accelerate processing faster and provide process isolation (more secure). It is a good design IMO with only one disadvantage that uses more RAM. I hated it at first but i welcome it now. Like Chrome vs older Firefox i guess.
AFAIK, WSL (Windows Subsystem for Linux) is going to be out of beta for RS3, making it a fully supported OS component. They also improved the console colors to work better with modern displays (but this is sort of UI-related, again). And, yes, they are going to remove ReFS support from the Pro-SKU, don't they (kind of a feature )? I guess there is not much in the box for professional users in this release. I still think two big updates a year is too much. I mean, they cannot even deliver all the features they plan for a release and postpone them all the time (the new people's experience, planned for RS2, for example) - so why not deliver a little slower, but deliver, instead?
If i understood correctly, they removed the ability to create ReFS partitions, still it will handle them properly. Was removed to have another argument for ProfessionalWorkstation SKU.
There are also significant security developments under-the-hood as well with a large amount of kernel level process mitigations and also hypervisor based security improvements.