docs,windows: emphasize that BAZEL_VS != BAZEL_VC

Fixes https://github.com/bazelbuild/bazel/issues/5272

Change-Id: Ia49c084f1fe036ff0e5b18fea096f31642cf8b5b

Closes #5280.

Change-Id: Ia49c084f1fe036ff0e5b18fea096f31642cf8b5b
PiperOrigin-RevId: 200005785

2 files changed, 11 insertions, 8 deletions

diff --git a/site/docs/install-compile-source.md b/site/docs/install-compile-source.md
index 1edfca04cd..7bea209861 100644
--- a/site/docs/install-compile-source.md
+++ b/site/docs/install-compile-source.md
@@ -85,9 +85,9 @@ Bazel binary, without an embedded JDK. You can copy it to a directory in the
 1.  Open the MSYS2 shell.
 
 2.  Set the following environment variables:
-    *   `BAZEL_VS` or `BAZEL_VC`: Set to the path to the Visual Studio directory
-         or to the Visual C++ directory, respectively. Setting one of them is
-         enough.
+    *   Either `BAZEL_VS` or `BAZEL_VC` (they are *not* the same): Set to the
+        path to the Visual Studio directory (BAZEL\_V<b>S</b>) or to the Visual
+        C++ directory (BAZEL\_V<b>C</b>). Setting one of them is enough.
     *   `BAZEL_SH`: Set to the path of the MSYS2 `bash.exe`.
 
         Do not set this to `C:\Windows\System32\bash.exe`. (You have that file
@@ -96,7 +96,7 @@ Bazel binary, without an embedded JDK. You can copy it to a directory in the
     *   `PATH`: Add the Python directory.
     *   `JAVA_HOME`: Set to the JDK directory.
 
-    For example:
+    For example (using BAZEL\_V<b>S</b>):
 
         export BAZEL_VS="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools"
         export BAZEL_SH="C:/msys64/usr/bin/bash.exe"
@@ -104,7 +104,7 @@ Bazel binary, without an embedded JDK. You can copy it to a directory in the
         export JAVA_HOME="C:/Program Files/Java/jdk1.8.0_112"
 
 
-    or
+    or (using BAZEL\_V<b>C</b>):
 
         export BAZEL_VC="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC"
         export BAZEL_SH="c:/msys64/usr/bin/bash.exe"
diff --git a/site/docs/windows.md b/site/docs/windows.md
index 6a9f1598a9..7cac379ade 100644
--- a/site/docs/windows.md
+++ b/site/docs/windows.md
@@ -39,8 +39,8 @@ Python and the Visual C++ compiler. If you need to auto-configure again, run
 
 You can also tell Bazel where to find the Python binary and the C++ compiler:
 - use the [`--python_path=c:\path\to\python.exe`](command-line-reference.html#flag--python_path) flag for Python
-- use the `BAZEL_VC` or `BAZEL_VS` environment variable. See the [Build
-  C++ section](#build_cpp) below.
+- use the `BAZEL_VC` or the `BAZEL_VS` environment variable (they are *not* the same!).
+  See the [Build C++ section](#build_cpp) below.
 
 ### <a name="build_cpp"></a>Build C++
 
@@ -65,7 +65,7 @@ To build C++ targets, you need:
         [known issue](https://github.com/bazelbuild/bazel/issues/3949),
         please upgrade your VS 2017 to the latest version.
 
-*   The `BAZEL_VS` or `BAZEL_VC` environment variable.
+*   The `BAZEL_VS` or `BAZEL_VC` environment variable. (They are *not* the same!)
 
     Bazel tries to locate the C++ compiler the first time you build any
     target. To tell Bazel where the compiler is, you can set one of the
@@ -87,6 +87,9 @@ To build C++ targets, you need:
     set BAZEL_VC=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC
     ```
 
+    The first command sets the path to Visual Studio (BAZEL\_V<b>S</b>), the other
+    sets the path to Visual C++ (BAZEL\_V<b>C</b>).
+
 *   The [Windows
     SDK](https://developer.microsoft.com/en-us/windows/downloads/windows-10-sdk).