The biggest difference is the layout and layout options.
The Minivan uses a somewhat idiosyncratic layout that is difficult to find sculpted keycaps for (e.g. GMK, SA) unless you buy one of the keycap sets made by TheVan. However I find it extremely comfortable. It has a "full" home row.
The Daisy is basically the JD40 layout. It does NOT have a full home row, meaning in the standard home-row hand position your pinky is resting on the big modifier key on the right.
Take a look through your preferred keycap sets and make sure they are compatible, or be prepared to live with the wrong row profile. Obviously something uniform like DSA or XDA will pose no obstacle. Note that SA bottom-row modifiers (aka Row 3) are the same profile as the home row, so 40% compatibility is usually easier with SA than with GMK, OEM, or DCS.
As for feel, the Minivan is a fairly rigid typing experience because it's a solid tray, but it's also more consistent than your typical Poker-style tray mount, because of the "ribs" running along the bottom of the case. The Daisy is a top-mounted aluminum-plate with only 4 mounting points, making for very soft typing. With the bigger keyboards, having so few mounting points makes it too soft, but on the 40% board it works out well. The anodization quality on both cases will be excellent.
