Qt Setup: what is "MinGW-builds 4.8.0 32 bit toolchain"?

[Guillaume21]

Hi,

I just installed Qt 5.2.0 for Windows (MinGW version) on a computer, and I was wondering: what does the checkbox "MinGW 4.8" under the checkbox "Tools" do? The description says "MinGW-builds 4.8.0 32 bit toolchain". What is it actually?
Because the checkbox which installs MinGW is the checkbox "MinGW 4.8 (32 bit)" under "Qt 5.2.0" I think...

Screenshot:
!http://img11.hostingpics.net/pics/942378qt52setup.png!

Thank you for your help.

[steno]

This is just a guess, but the check box under the tools is the actual minGW compiler and the other is the Qt libraries built with the minGW compiler. I think it's just there just in case you don't have minGW installed already.

[Guillaume21]

[quote author="steno" date="1387219790"]This is just a guess, but the check box under the tools is the actual minGW compiler and the other is the Qt libraries built with the minGW compiler. I think it's just there just in case you don't have minGW installed already.[/quote]
I did the setup twice: once with MinGW 4.8 checked, once without checking it. Both installations have MinGW installed.

Furthermore, the size of the 2 installations are almost identical: the installation without "MinGW 4.8" is just a little lighter than the other (about 1.5 MB lighter).
I found out that this is the folder C:\Qt\Qt5.2.0\5.2.0\mingw48_32\doc which is lighter. All files (.qch) are a few KB lighter than the ones with "MinGW 4.8" checked.

It seems it's the Qt documentation... but what's the difference with the other installation and why is it called "MinGW-builds 4.8.0 32 bit toolchain"?

EDIT: actually I reinstalled both installations again and there is no size difference (there was a difference probably because I opened the examples or something like that). They're SAME.
So what's this toolchain thing?