XChain is not racing to be another execution chain. It composes proven parts — Cosmos consensus, Celestia-style DA, rollup-style proof aggregation — into a tiered foundation. So before placing anyone, fix the axes; the comparison then reads as classification, not advertising. The axes are the three Layers defined in Architecture: Settlement (finality + proof aggregation) · Execution (double-spend protection, composability) · Data (append-only logs, no per-record consensus). The fair question for every system, XChain included: which Layers does it cover, and where does it leave a gap?

Key: ● present / a focus · ◐ partial / left to others · ○ absent.

System	Settlement	Execution	Data	What XChain adds
Monolithic L1 (Solana…)	●	●	● (merged)	No Domain split ⇒ cheap data still pays expensive consensus. XChain tiers by value.
Ethereum (rollup-centric)	● (L1)	◐ (fragmented rollups)	◐ (blobs/EIP-4844)	A non-consensus Data Layer for high-volume low-value data; security by asset class; READ/WRITE split.
Cosmos / Interchain	○ (each chain sovereign)	● (app-chains + IBC)	◐ (each chain self-stores)	A shared Settlement (root + ZK aggregation) and a dedicated Data Layer + tiered assurance. XChain reuses this stack.
Polygon AggLayer	● (proofs aggregated on ETH)	● (chains + pessimistic proof)	◐	A Data Layer + per-asset security + READ/WRITE split. (XChain borrows the pessimistic-proof idea.)
Celestia	○	○	● (modular DA, its focus)	Uses DA as the Data Layer, then adds Execution + Settlement with real security on top.
Polkadot / JAM	● (shared relay)	● (parachain/core)	◐	Keeps locality + tiering to not lose composability; an explicit Data Layer for cheap data.

Architectural positioning, not a performance benchmark.

Reading it: Celestia is strong at exactly one Layer (Data) and leaves the other two to others — XChain fills them. Cosmos gives excellent Execution + interchain but no shared Settlement; XChain adds a common finality root. Ethereum-rollup and AggLayer cover Settlement + Execution well but lack a non-consensus Data Layer for cheap data — the biggest gap XChain targets. Monolithic L1 covers all three but merges them, so every datum bears the same cost.

The matrix also shows, cell by cell, the three contributions enumerated in the Introduction: the UAC-enforced 2-Domain boundary (no other system makes its data layer structurally value-free), the READ/WRITE split (cross-chain reads near-unlimited over ICQ, only WRITE pays), and value-proportional security by Tier.

Takeaway: XChain does not replace these systems; it unifies each one's strength into one tiered framework — a genuinely cheap Data Layer bound to a genuinely solid Settlement Layer. One resource has been left deliberately undescribed until the mechanism was complete: the coin that meters the machine.