When you share a Live Photo from an iPhone using MMS (Multimedia Messaging Service), the image is automatically converted into a standard still photo. In this process, the file loses its metadata, motion, and higher resolution quality. MMS simply doesn’t support the advanced format that Live Photos use, so what the recipient receives is a compressed snapshot rather than the full interactive experience.
By contrast, iMessage is designed to preserve the integrity of Live Photos. When sent through iMessage, the photo retains its motion, sound, and metadata, allowing the recipient to view it exactly as intended. This makes iMessage the proper channel for sharing Live Photos, while MMS should be considered a fallback option for basic image delivery only.