Backing up does not have a strict definition. When you hear the term "back up", you should ask "back up what?" The speaker might mean Windows or the speaker might mean personal files or who knows what else.
Some people use it synonymously with making a system image. Others mean a backup of their personal data. I think the Windows built in tool does both.
A system repair disk is something else entirely and is a means of repairing Windows as opposed to restoring the entire Windows partition (which is what imaging normally does).
My Computer
Computer type
PC/Desktop
Computer Manufacturer/Model Number
Ignatz Special; 4 speed manual gearbox; factory air conditioning; one of one
OS
Windows 7 Home Premium SP1, 64-bit
CPU
Intel Skylake i5-6600K, not overclocked
Motherboard
AsRock Z170M Extreme 4, micro ATX
Memory
8 GB HyperX DDR4-2666 (2 x 4 GB)
Graphics Card(s)
none; graphics are integrated on CPU
Sound Card
onboard: Realtek ALC1150; external: USB Behringer UF0-202
Monitor(s) Displays
Dell S2340M 23 inch IPS
Screen Resolution
1600 x 900
Hard Drives
System: Crucial MX100 series SSD, 128 GB;
Data: Samsung Spinpoint 103SJ, 1 TB;
Backup: WD Caviar Green WD30EZRX-00D8PB0, 3 TB
Microsoft Security Essentials and Malwarebytes Premium
Browser
Pale Moon
Other Info
All fans PWM; speeds at idle: CPU circa 500 rpm; intake circa 600 rpm; exhaust circa 600 rpm; CPU temps 27 idle and 47 C load in a warm room (27 C/81 F) when running Intel Extreme Tuning Utility stress test.