Cashews are really kernels, they are closer to tubers in the way that the thing you eat is a reservoir of carbon rich material, and attached to it is small organs that can feed on the kernel or starchy mass
Seeds are the same but much higher density of the ... Well, it's basically an embryo of callus, the undifferentiated tissue that can specialize according to conditions (gravity, light, moisture), seeds are much more this general tissue and less the actual nutrients.
So they are mostly immune system, essentially.
The seed strategy is vires in numeris, the tuber and fruit (and nut) have the "eggs in one basket and watch it carefully" strategy.
It is a lot like distributed systems architectures too... Bitcoin has many replicas, and avoids easy gaming of leadership selection (the function of the embryo) in a like way as the seed with it's limited time window to start a new plant.
Seeds are decentralized, kernels and nuts and tubers are like raft and Cassandra and dynamo...