What is the difference between match balls, training balls and special balls?

Match balls: very high quality, excellent play characteristics, use of the latest/most innovative materials and manufacturing methods, certified to association standard (e.g. FIFA, IHF, DVV, etc.)
Training balls: high-quality balls, very good play characteristics, extremely long life, use of robust and hard-wearing materials, easy-care, particularly suited to everyday training activities
Special balls: specially developed balls for use in certain conditions.
Examples: indoor, floodlit, lightweight, heavyweight