Usually it's fine if you're using the same base from the same modder (eg: 8.4.300_v1 to 8.4.300_v8), but values change between base versions (eg: 8.4.300 to 8.4.600), so while you can load the config and doing that usually doesn't cause issues, the app won't be using many of the settings/values that the config is supposed to change. This might end up changing the look of your pictures.
Configs from very different versions don't work at all because too many things change behind the scenes. For example, a config from GCam 7.3 can't configure GCam 8.1.
Configs also aren't compatible between devs. A config for BSG 8.4 probably doesn't work on BigKaka 8.4. The exception is when someone takes a version and makes small changes to it (eg: UltraM8 using Arnova8G2).