Confused about my web stats via Jetpack

I am getting wildly different web stats from Jetpack and was hoping you could help me clear up my confusion. When I look at Jetpack "Site Stats", I get anywhere from 15 to 65 views per day for my website. But when I scroll down within Jetpack to "Blog Statistics" I see daily visitor numbers such a 139 or 165 and page views totaling 1,000 or 1,300 per day. Then when I scroll down to "Post Views" I consistently see 500 per day. And on one day – April 7 – I see a huge spike in "Post Views" of over 3,500 even though "Site Stats" shows fewer than 20 page views on that same day. I have attached the images I am referring to. Can you help me make any sense of this?