Whay gives Lenovo windows 8 laptop so much storage?

My Lenovo laptop has 320 go and 25 go on recovery. What give it this much storage?
I ask because it's not connecting to my Wi-Fi so I want to take the hard drive out and put it into my old laptop. But the drive only has 4 gb…

You could do that, but then Windows would not work. The EULA says one installed Windows per machine. You can't make the Windows 8 from the Lenovo work in your "old laptop" because it has a different motherboard.
320 GB is not large. There are many laptops with 500 GB or 1 TB.
The connection to the Wi-Fi is not depending on the laptop. It is depending upon the settings in Windows. And those will travel with the hard drive.