Newbie confused about special carts for Kandypens

Ultimately, I wanna know if there are any pre filled 510 oil carts that are compatible with the kandypen, or what to even ask for at a vape shop.

So I have an ooze pen slim twist pro and a kandypen slim. They both accept 510 threaded oil carts, but the ooze pen works by pushing the button and the kandypen works automatically just by taking a hit.

The carts I've been getting work fine for the ooze pen. But they don't work in the kandypen. The (empty) cart that came with the kandypen works, and I guess I'm supposed to just keep refilling it with oil. It came with two little plastic bottles for doing that.

But why don't the carts work for both pens? Is it different technology? I'm a clumsy guy and I'd prefer not to deal with refilling the kandypen cart. It'd be nice if there were prefilled carts that are compatible with the kandypen slim. Can anyone help a noob out?

Unfortunately I don't live in an area with vape shops I can trust, so I'm counting on this sub! Thanks in advance.