Image Metadata is in your image files. Bridge keeps Image information in its caches. If missing bridge will build its cache. If you use Adobe bridges distributed caching the bridges caches ares stored in two files in each of you image folders. ACR keeps you RAW file conversion settings in an ACR database or in ACR sidecar files which are stored in the same folders as your RAW files and perhaps bridges caches. These settings are also stored in conversion image files metadata.