Larger Private Data reserved in Win10 compare with Win7

Question

I run the same application on Windows 10 and Windows 7 (both 64-bit) and used Process Explorer to monitor the Virtual Size. I noticed that the Virtual Size of the application running on Windows 10 is much larger than running on Windows 7.

By using VMMap, in Private Data:

Windows 10 - 1 address with 4.2GB is reserved and not committed.

Windows 7 - 2 address with 15MB are reserved and not committed.

So my questions are:

1. Why there is a large memory has been reserved? Is it just a different memory management done by Win10 and Win7?
2. Or, there is something to do with the application that I ran? (The application has no problem to run on Win10 & Win7)
3. Is there any suitable indicator to track memory leak? (Eg: 'Committed' value in VMMap) It seems like so much discussion/argument on this :P