Run level 3 is set to multi-user.target and run level 5 is set to graphical.target.

To verify your default run level use below command,

# ll  /etc/systemd/system/default.target

How can switch to "Runlevel 3"
 
# systemctl isolate multi-user.target
 
# ll  /etc/systemd/system/default.target
lrwxrwxrwx 1 root root 40 Feb 26  2015 /etc/systemd/system/default.target -> /usr/lib/systemd/system/multi-user.target


How can switch to "Runleve 5"
 
#  systemctl isolate graphical.target

# ll  /etc/systemd/system/default.target
lrwxrwxrwx 1 root root 40 Feb 26  2015 /etc/systemd/system/default.target -> /usr/lib/systemd/system/graphical.target