Every app has data and cache.
In Android, what is the difference between the two?
App developers decide what information to be kept in "data" and what to be kept in "cache".
Usually, "data" is used for account info, settings, saved activity data, game scores, and whatever is need to be kept permanently. Clearing data will make your app "forget" everything like you have reinstalled it.
"Cache" holds all information and files that can be retrieved somehow (from the internet, or other way). For example social apps can cache all your feed data (photos, comments, and so on). Clearing cache may lead your app to reload all the lost (and necessary) data from it's original source. It shouldn't make your app behave bad.
Cache is temporary files. One example might be thumbnails for contacts in a social media app. These can be cleared without any major effect — the app can just download them again when it needs to — and if space is low the Android OS may remove cache files itself.
Data is the "important" information. This might include credentials and settings that you generally want the app to remember.
Cache are temporary (unnecessary) files, whereas data are files required by the application. It saves users activity and progress
Consider clearing the cache more often, otherwise it may affect the device performance. When cache memory increases, phone becomes slow and laggy. It happens with phones having low internal memory.