Why is the ping lower on my phone than it is on my laptop?

To start off, I'm using my wifi on both my phone and my laptop. Anyways, whenever I do a speedtest on my phone the ping is always 11ms, but whenever I do a speedtest on my laptop the ping is anywhere between 30 and whatever ms. I literally just did a speedtest on my laptop and got a 112ms ping! Why is the ping different on my phone and laptop and why does it change on my laptop so often?? Also, does speedtest.net test wifi speeds?

It depends on what site or app you are using and whether the phone is using WiFi or Cellular when you are running the test.