"Dutch" is a more relaxed riding position with a lower seat position and the handle bars set higher. English 3 speed has a slightly more aggressive position higher seat position, low hand position. Yes we aren't talking much, but it's a difference.
A Dutch
An English
I should note that both bikes pictured above are made by Linus.
Dutch also usually comes with all accessories fenders, bell, lights. chain guard, skirt guard...etc. English 3 speeds were mostly just bike and fenders and chain guard. Of course there were exceptions (like the Superbe). But on the whole this would apply.
Of course the obvisous answer is the English bike were made in England, and the Dutch bike made in Dutchlandia.