Differences between gcc versions 4 and 5 and 6 [closed]

Question

When downloading sources for an arm cross-compiler I found that there are several versions of gcc in maintenance. Latest builds are v4.9.4, v5.4.0 and v6.2.0.

Why is there a v4 that is more recent than the latest release of v5 and the first release of v6 and what are the major differences between these versions?

Answer 1

The older versions receive bug fixes only, while new features are implemented in the newer versions. From https://gcc.gnu.org/releases.html:

The table is sorted by date. Note that starting with version 3.3.4, we provide bug releases for older release branches for those users who require a very high degree of stability.

If you like it graphicly (ASCII-ART): https://gcc.gnu.org/develop.html#timeline