Have you ever used backup and restore in Vista?
Time Machine is like both Backup and Shadow Copy together, with a much simpler user interface. It does a full backup every hour. That would normally fill up your backup drive fast, but only changed files get copied, non-changed files only get a new hard link in the backup folder. OS X also has a service that constantly looks for changes in files. This feeds both Spotlight and Time Machine.
Yes. It is not the same, or as easy, as Time Machine.