What's the differents between differential backups and incremental backups

What's the differents between differential backups and incremental backups?
I have Acronis True Image 11 and have chosen the differential backups after
a Full image was taken. But it seems as if both do the same thing, I can't
tell the difference between them.
Thanks again in advance for any help on this subject...
Mike...

 

A differential backup takes all files that changed after the last
full backup.
An incremental backup takes all files that changed after the last
backup.

So, if you run daily backups on a weekly schedule with a full
backup on friday night, your differential backup will constist of
monday's changes
monday's changes + tuesday's changes
monday's changes + tuesday's changes + wednesday's changes,
etc.

While incremental backups will consist of:
monday's changes
tuesday's changes
wednesday's changes,
etc.

So, your incremental backups will be more compact, but you will
need each and every incremental backup to restore.

Differential backups take more storage medium and time. But you
only need the last differential backup to restore.
Apart from the full backup, that is. In both cases

Seasonal greeting: "that you may never _need_ your backup"