Special occasion rituals are different from the very start because they are generally controlled by events in our lives, rather than by cycles or rhythms of nature. Yes, they may include calendrical factors (a rite for the first day of school, or a birthday, or an anniversary), but generally, these sorts of rites either occur or get thier start as a result of life happening in unplanned ways.
Perhaps it is an accident of American life, but few life-events are ritualized at all: weddings and funerals are the only two "required" rites in an American's life. We rarely do rituals for the "other" passages, though we commonly celebrate birthdays and anniversaries, which merely mark the passage of time, rather than the passage of human beings from one state to another.
To that end, the difference in writing and performing special occasion rites seems to be based in a notion of necessity: we feel we need rites to celebrate the eight High Days (and weddings and funerals), but we feel we do not need a ritual for sending our child to the first day of school, getting her ears pierced, or picking out a prom dress.
Another large difference is, by their very nature, special occasion rituals must fit into life in a way that a High Day does not. High Days take us to the center of the worlds at specific and predictable times, while special occasion rites drag us to the center at times we do not generally plan out: birth is an accident of conception time (and some babies are earlier than others), losing a first tooth can occur on any given day, and a child will start dating when they are good and ready (I imagine that no parent manages to plan for that in advance). Because of the timing issues, these rituals tend to have less structure even while having deeper meaning. Fitting a ritual into the hustle and bustle of a child's first day of school can be hard, but it can also be ritualized simply in reaction to the constraints.
Thus an important part of performing special occasion rituals is acknowledging that they are both important and necessary. They have value, and we need to recognize that value. In doing so, we may find that, aside from a need to fit them into daily life (rather than fitting our daily lives around the High Day dates), they are very similar to the regular rites of Our Druidry.
