Honestly I'd say the biggest difference is that while ours have better craftsmanship, they simply have better access to wood.
...REALLY stretching there.
Our boats are lightweight, fragile, and have a maximum size capable of holding one or two people.
The most advanced boat is a dugout, a single log whittled into a reasonably seaworthy shape and then you dig/carefully burn a hole into the boat using a great deal of time and manual labor, to house a few people. OR a canoe, made using the bone and leather of larger animals in a single piece. This is durable enough not to be casually broken or sunken by anything heavier than calm seas, but still easily capsized, as we've done with Saiga's vessel.
The most common boat is made of leather strapped to a bone frame. Their sole merits are that they float and are light. They have great difficulty going further than near-coastal waters. This type of boat is not strictly speaking watertight.
Our boats are not ocean-worthy for more than a mile out to sea, if at that. The most common boats can't even go out that far, as they aren't even fully watertight when burdened. They're purely coastal vessels that move up and down the coast.
Their boat(comparing to our dugouts/canoes, because this is likely to be their best vessel rather than their mook vessels) is stable enough to cross miles of ocean, carrying five times the load of our boats.
It's comprised of composite construction when our boats are single piece.
Yes, they have more wood, but we also have wood(we actually rely on wood to survive the winter). Saitev has an actual forest over in his parts, and the dugout requires a fair sized tree to create compared to a raft, which can be build out of multiple smaller trees.
The main challenge here is each of the parts.
-Figuring out rope takes innovating with grass. To braid and weave them into a stronger form. Keshketev probably knows about rope, and if the Essence Drinkers get domesticated, I suspect we'd have silk ropes for our best work. You need rope over rawhide since it can be extended indefinitely, whereas rawhide or leather strips have a maximum length limited by the source animal(which means you're also scrapping good leather), discouraging the heavy use of long bindings. Rawhide also rots and loses strength pretty fast when wet compared to vegetable fibers.
-Figuring out log and plank construction requires significant amounts of wood to work into structures and some spirits interested in blessing the process. It means the possibility of building larger structures than single piece materials allow for. There's probably some of this already, but lack of rope, lack of cutting tools for joints, and obviously lack of nails means it can't progress.
-Assembling a raft itself requires the above two in practice enough for someone to try out the floatation qualities of lashed logs and branches.
Calling our vessels better made is a little like comparing log rollers to a wagon. We spend a lot more effort to get less done.
On the other hand! With the Divine Realm enhancing Innovation, we can spend a Decree slot to make people go in there to make something new...well, once we stabilize it with amenities. For now we can maybe show it off to Seski