OpenSSL binary distribution: meaning of the char at the end of version

Question

I am using libcurl which depends on OpenSSL thus I need to link with it too.

There are binary distributions for Windows here, but I do not understand what does the character at the end of the version stands for (packages named like: Win32 OpenSSL v1.0.1b, Win32 OpenSSL v1.0.0i, ...).

I might miss something but quick lurking through site/page gave no explanation about that.

What is the difference between them?

Answer 1

See OpenSSL Support FAQ 8: How does the versioning scheme work?:

After the release of OpenSSL 1.0.0 the versioning scheme changed. Letter releases (e.g. 1.0.1a) can only contain bug and security fixes and no new features. Minor releases change the last number (e.g. 1.0.2) and can contain new features that retain binary compatibility. Changes to the middle number are considered major releases and neither source nor binary compatibility is guaranteed.