Patient Portal. Patient portals are access points (small clouds) to information in each provider’s EHR. Control of the health information (and operational information, e.g., appointments) is maintained by the providers, and there is no substantial integration of the health information across providers.
HealthVault. HealthVault (large cloud) is a platform for safely storing, managing, accessing, sharing, and integrating health information from numerous sources, including providers’ EHRs. HealthVault is not a PHR; rather, it is a container–a place and a health information technology (Health IT)–with information organized into one or more personal health records (PHR). Information in a PHR is managed and controlled by the patient, not the providers. HealthVault enables the integration of health information from many sources, including providers’ EHRs and such other sources as web-based and mobile device apps and personal health devices, e.g., patients’ blood pressure, heart rate, and glucose monitors. Consequently, a PHR may be a more complete and accurate health record than any single EHR.
More on this. For a more thorough explanation of these differences, see the source of these two graphics, Microsoft HealthVault vs Patient Portal vs PHR For Meaningful Use. Another, tabular distinction is made in this graphic.