which QNX to download?

Hi all,
I am not sure which QNX ISO I should download - 6.1.0 or 6.2.1.
File size of 6.1.0 is about 440MB.
6.2.1 is 287MB large.
Since 6.2.1 is smaller in size, is it in any way incomplete as compared to 6.1.0 (which is larger). Also do both come with C/C++ compiler & debugger with support for POSIX threads?

Thanks in advance.
AMIT

The main difference is the number of platforms supported. In 6.2.1 there is only x86 and arm while 6.1.1 had mips and ppc as well.

so why the difference in file sizes?

Because 6.2.1 doesn’t include all the binaries for ppc and MIPS and sh? Each one is 100-150M.