Hi! Welcome to DT from Colorado.
To some extent, puppy size doesn't necessarily mean that he will stay that way as he matures. I mean, the runt of the litter may even outgrow the others as he matures. Your pup looks a bit tubbier than the other puppy 😉 so that may be all you're seeing. They also look a bit younger than 9 weeks in your picture.
But he'll grow into what he'll grow into. And unless you're planning on showing your pup in conformation, you're not likely to see that much of a difference when they are both adult.
He's obviously all doberman, and cute to bat.
To some extent, puppy size doesn't necessarily mean that he will stay that way as he matures. I mean, the runt of the litter may even outgrow the others as he matures. Your pup looks a bit tubbier than the other puppy 😉 so that may be all you're seeing. They also look a bit younger than 9 weeks in your picture.
But he'll grow into what he'll grow into. And unless you're planning on showing your pup in conformation, you're not likely to see that much of a difference when they are both adult.
He's obviously all doberman, and cute to bat.