Weird Traffic Patterns, do you notice this?

I have multiple sites but I when comparing 2 sites I see this.

800 Unique visitors a day on spot 5 in G for a keyword that only get 25,000 a month searches.

50 Unique visitors a day on a spot 4 in G for keyword that get over 500,000+ a month searches.

I am only converting on the site that gets more visitors yet has less searches. It is kinda strange since I know for a fact 2/3 position for the keyword that is sitting in 4th place right now can easily make $200+ a day I make about $5. Anyone else see things like this?

Poor quality traffic...Poor quality keyword..Not sure what niche you're in or what keywords they are but id say that your chasing the wrong keywords with the higher searched site...Its all about quality over quantity...