Quick question about NetBSD source code

[Alexey Smirnov <ramyalexis%gmail.com@localhost>]

Hello

Go a quick question here.

On the documentation we have several types of geting src.

First is to download five archives from

ftp://ftp.NetBSD.org/pub/NetBSD/NetBSD-6.1/source/sets/

Seconf is do download a lot more from
ftp://ftp.NetBSD.org/pub/NetBSD/NetBSD-release-6/tar_files/src/

What is the difference between them in code ?

Thank you.