Question about Infrasrtucture Monitoring vs Host Monitoring

So this might be a dumb question..   but we recently upgraded OEM to the latest version and it appears the Systems Infrastructure Server plugin is now a default and with it it's own batch of metrics that get alerted on.  I'll be the first to admit I get confused by how the metrics and notifications and what not all work together, but I have it working from some internet articles and some Oracle docs, but the new alert under that plugin alerts when the server is down, and we already have alerts for when the host is down from the