The Project Structure I designed in VS:

bin             // Output Files and Third-Party DLL 
     win32
     win64
include         // Third-Party Headers
lib             // Third-Party Library
     win32
     win64
src             // Source Files
     QtSolution          // Solution Folder
         QtProject1      // Project Folder
            build        // Intermediate Folder

First, I created a QtWidgetApplication in Visual Studio.
Then, I made some changes in Project Properties. 
(1) Output Directory: $(SolutionDir)..\..\bin\win32
(2) Intermediate Directory: $(ProjectDir)build\$(Configuration)
(3) Working Directory: $(SolutionDir)..\..\bin\win32
(4) Additional Include Directories: $(Solution)..\..\include
(5) Additional Library Directories: $(Solution)..\..\lib\win32

Something wrong with "Create Basic .pro File"

After setting up the Project Properties, I build the project and run the ouput executable. It works successfully. And then I pressed "Create Basic .pro File" so that I could open and edit in QtCreator (if I want to). However, in the .pro file that VS created, I found that

DESTDIR = ../../bin/win32
LIBS += -L"$(SolutionDir)../../lib/win32"
DEPENDPATH += .
MOC_DIR += .
UI_DIR += .
RCC_DIR += .

Moreover, After opening .pro file with QtCreator, I tried to build the project, but an error showed up:

error: C1083: 無法開啟包含檔案: 'ui_qtwidgetsapplication1.h': No such file or directory

Indeed, After I checked the Intermediate Folder created by QtCreator, I didn't find 'ui_qtwidgetsapplication1.h'.

It looks like that
the directory of Generated Files created by Visual Studio are: (Inside the Project Folder)

$(ProjectDir)build/Debug/moc/
$(ProjectDir)build/Debug/rcc/
$(ProjectDir)build/Debug/qrc/

And the directory of Generated Files created by QtCreator are: (Outside the Project Folder)

$(ProjectDir)../build-QtWidgetsApplication1-Desktop_Qt_5_15_0_VS2019_32bit-Debug/debug/

Questions I sorted out to ask

It looks like that Visual Studio has some bugs when "Creating Basic .pro File".

(1) Why doesn't DEPENDPATH have "$(SolutionDir)../../include"??

(2) Why doesn't DESTDIR have "$(SolutionDir)"?? 

(3) Does $(SolutionDir) work in QtCreator? (I guess not) Then, Does that mean that I had better not use VS-default variables in Project Properties?? 

(4) Why MOC_DIR, UI_DIR, RCC_DIR are "."??

(5) Why didn't QtCreator create 'ui_qtwidgetsapplication1.h'?