Understanding how the plugin shows stats

I looked at some web hosts where this plugin shows stats in this format
Cache: X Objects
While on most hosts, this plugin shows
Cache: XX MB OF X MB

I noticed this difference even when the redis.conf was almost the same with the same cache eviction policy.

1. Could you please explain if there’s any difference?
2. Could you also recommend what would be the ideal configuration for maximum retention of redis data?

Thanks a lot for your work!