First Windows 8.1 GA upgrade was an updated ESD, and it already had 5 refreshed ESD upgrades it's safe to persume Windows 10 will have the same
How does education differ from pro? nm, I just found this "Windows 10 Education builds on Windows 10 Enterprise, and is designed to meet the needs of schools – staff, administrators, teachers and students. This edition will be available through academic Volume Licensing, and there will be paths for schools and students using Windows 10 Home and Windows 10 Pro devices to upgrade to Windows 10 Education." pfffft
Maybe they'll do the same as with Visual Studio. It came out yesterday and was available right after on MSDN. I assume that the "After" on Gabe's sentence is that after they push the button to start the GWX upgrades they'll also push the button on the subscribers page, making ISO's available as well. But... that's only my honest opinion.
Some guys had asked if his Windows is activated, does it mean it is licensed/genuine, I'll give a simple example: Suppose you have a ticket to a show, but it's fake(or void), if you got thru the ticket check at entrance, you are "activated" and could enjoy the show, but the audience license doesn't apply to you, and you are not subject to the rights/restrictions stipulated in the audience agreement, if you were caught using a non-legit ticket, the theatre simply kick you out.
in other words, if your windows isn't activated legit, MS will take your activation and G it TFO Unless they cannot tell legit from naught LOL
MS doesn't want to have any problem with people who did pay, so they try their best in the "ticket check at entrance", but doesn't give a sh*t to people already "inside the theatre".
Seems if you upgrade to 10240 and login with MSA(Insider registered), you could enjoy a fully activated RTM for the full month of Aug. I heard that the post-RTM Preview is planned for Sept, naturally, take with salt. No comment on folks who didn't login with MSA and got "activated permanently".