Scientific Linux is a recompiled Red Hat Enterprise Linux, co-developed by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN). Although it aims to be fully compatible with Red Hat Enterprise Linux, it also provides additional packages not found in the upstream product; the most notable among these are various file systems, including Cluster Suite and Global File System (GFS), FUSE, OpenAFS, Squashfs and Unionfs, wireless networking support with Intel wireless firmware, MadWiFi and NDISwrapper, Sun Java and Java Development Kit (JDK), the lightweight IceWM window manager, R - a language and environment for statistical computing, and the Alpine email client.
Scientific Linux 7 ISO images
Please review the Scientific Linux Release Notes

Scientific Linux 7 provides a few install images:

SL-7-Everything
A complete install tree suitable for offline installation. This image is unlikely to fit on standard optical media.

SL-7-Install-Dual-Layer-DVD
Install media suitable for use on Dual Layer DVD media.

SL-7-netinst
Install media suitable network install.

SL-7-DVD
A link to SL-7-Install-Dual-Layer-DVD.

SL-Live
Scientific Linux 7 Live media.

SHA*gpgsigned
Signed copies of the SHA sum files. They are signed with the packaging key.

https://www.scientificlinux.org/
http://ftp1.scientificlinux.org/linux/scientific/7x/x86_64/release-notes/