Software Collections are never versions of system wide packages used typically on Red Hat Enterprise Linux. They are installed together with the system-wide versions and can be used to develop applications without affecting the system tools.
If you need to use a software collection then enable it like so:
scl enable rh-ruby22 /bin/bash
You can enable a second (and third, etc) software collection by executing
scl enable nodejs010 /bin/bash
After executing the above two commands I have:
$ which ruby /opt/rh/rh-ruby22/root/usr/bin/ruby $ which node /opt/rh/nodejs010/root/usr/bin/node
Now I can develop an application using Ruby 2.2 and Node.js 0.10.