When you compare WombatOAM to Prometheus, WombatOAM surfaces a lot more metrics.
WombatOAM also collects logs from different sources (e.g. lager, sasl, elixir_logger etc.).
Wombat raises alarms (not just simple alarms, but users can define log based alarms with pattern matching, raise their own alarms), there are tools in WombatOAM (Process manager (Etop), Table viewer (ETS), Mnesia, MongooseIM related tools)
There are a lot of integrations, just to mention some of them: Logstash, Zabbix, DataDog etc., so Wombat can send the collected data to these products.
WombatOAM can handle different users with different roles and rights.
There’s a lot more that we could point out - let me know if you want to know more!