The distinction between authoritative and authoritarian parenting styles is subtle, yet crucial; it displays more of a degree than a method itself. The former denotes an imposing and respected approach, where the latter speaks more towards angry demands and even harsh discipline.
Authoritative parenting is what generations past have used, and quite effectively. Authoritative parenting means that the parents are in charge, the parents make the rules, and the parents enforce the rules. There are no questions asked, and little information given, and this is both accepted and expected.
Parents who raise their children in this manner have respectful, obedient children; ones who know what to expect and are therefore secure. These children know they are loved, they know that their parents do indeed care. They are not, however, "friends" with their parents; they have friends their own ages, and this is appropriate.
Authoritarian parenting, on the other hand, exhibits these same characteristics but in a far more heavy-handed manner. Children are frequently spoken to as though they are wrong, even though they may not be; children, too, can be subjected to harsher, even physical, discipline. This is not to say that physical discipline is bad, as discipline simply means to "teach and correct", but that sometimes the punishment does not fit the crime.
Authoritarian parenting will often deny the child his feelings and emotions; this style of parenting emphasizes a hands-off approach to relationships and emphasizes the parental role as that of a totalitarian ruler. Authoritative parenting, conversely, resembles that of a benevolent dictatorship.
The parents who choose a benevolent approach will reap the rewards of having children who, when younger, will be the ones who say "please" and "thank-you"; they will be the ones who have a good work ethic and who succeed in school because they wish to please their parents. The parents who choose to rule by fear will see quite different results: their children are likely to respond out of that fear, which will only last as long as they are small; these children will likely rebel in serious ways as they age, and finally will be apt to leave home early and cut parental ties as quickly as possible.
Yes, there are great differences in these two styles, but the largest disparity is in the end product, the end result: the children.
An authoritative parent will retain the love and respect of his children and, when they reach adulthood, they will continue this tradition with their own children. An authoritative parent will know he has done his job, and done it well, in the raising of those children, because the relationships that were built will last forever.
The authoritarian parent, however, may be greatly surprised at the things his children remember and retain, and be perplexed over what he did wrong. He will likely have little contact with these children when they are adults, and they will no doubt adamantly raise their children in the opposite manner; permissiveness is nearly as negative a parenting style as authoritarian.