What is the difference in Mediation Adapter and Adapter?

[rajsuvariya]

I see there are two different adapters present under InMobi and MoPub. One is MediationAdapter and one is Adapter. By looking at the code it seems that the MediationAdapter only supports Rewarded Ad whereas Adapter supports the rest of the formats. Any specific reason to do so?

FYR: https://github.com/googleads/googleads-mobile-android-mediation/blob/master/ThirdPartyAdapters/inmobi/inmobi/src/main/java/com/google/ads/mediation/inmobi/InMobiMediationAdapter.java