Scoring and creasing are often used interchangeably, but they actually refer to slightly different processes. Scoring compresses the paper to weaken it along a line, making it easier to fold neatly. Creasing delaminates the paper fibers to produce a clean fold in more difficult cases.
Scoring machines roll a wheel along the paper to produce a scored line. Scoring is a common option on many folders, perfing machines, presses, etc. This method works best on thin papers and conventional printing.
Creasers use a solid bar to crease the whole line at once. Creasing is much less likely to result in cracking of digital prints or wrinkling of thick or coated stock. Creasers are recommended for anyone doing digital printing, or where coated or other difficult stock is used.