| Governance & Authority | IMO (MARPOL Annex VI, Reg. 27). | European Union (Regulation (EU) 2015/757 as amended). |
| Geographic Scope | Global (All international voyages). | Regional (Voyages to, from, and between EU/EEA ports, plus emissions at berth in EU ports). |
| Ship Size Threshold | ≥5,000 GT (engaged in international trade). | ≥5,000 GT (Expanded to general cargo & offshore ships ≥400 GT for reporting). |
| Target Gases | Originally CO2 only (Enhanced DCS includes life-cycle WtW metrics). | CO2, Methane (CH4), and Nitrous Oxide (N2O). |
| Reporting Granularity | Annual aggregated data per calendar year (no per-voyage breakdown). | Per-voyage reporting AND annual aggregated data. |
| Transport Work Proxy | Design Deadweight (DWT) / GT × Distance Sailed. | Actual Cargo Carried (or passenger count) × Distance Sailed. |
| Data Verification | Flag State or Recognized Organization (Class/RO). | Independent accredited EU MRV Verifiers. |
| Data Portal / System | IMO GISIS Database (via Flag/RO). | THETIS-MRV database. |
| Public Transparency | Anonymous aggregated database (individual ship names hidden). | Publicly accessible ship-by-ship emissions data. |
| Compliance Certificate | Statement of Compliance (SoC) (valid for 15 months). | Document of Compliance (DoC) (valid for 18 months). |
| Underlying Plan | SEEMP Part II (Ship Energy Efficiency Management Plan). | EU MRV Monitoring Plan (assessed by verifier). |
| Policy / Financial Link | Feeds directly into IMO CII ratings (MARPOL Annex VI). | Feeds directly into EU ETS (allowance surrender) & FuelEU Maritime. |