XChain stands in a tradition of "aim enormous, ship step by step." Its nearest relatives — and where it differs:

System	In common with XChain	Where XChain goes further
Ethereum (rollup-centric)	Scale via many chains, modular	Adds a non-consensus data base for the ocean of volume
Cosmos / Interchain	App-chains, IBC, sovereignty	Is a shared base + assurance tiering (and builds on Cosmos)
Polygon Agglayer	Aggregated chains, pessimistic proof	Adds the Data Layer + security-per-asset + the READ/WRITE split
Celestia	Modular DA, data availability sampling	Uses it as the Data Layer, adds a secured execution layer
Polkadot / JAM	Shared security, many chains	Avoids lost composability via locality + tiering

Takeaway: XChain is not competing to be another execution chain. It composes proven parts into a layered foundation others build on.