I went to a workshop awhile ago where the topic of the difference between a spell and a ritual arose. The discussion went for quite awhile and the final conclusion was that a ritual was done with the guidance of deity. The way this questionable resource helps is to define a difference between a ritual and a spell through omission.
Rituals do have a more religious element.
They are the periods where someone examines their perceptions without worrying about possible results. A person doing ritual can light a candle for the pleasure of lighting a candle while someone performing a spell has to know why the candle is there and what its color represents. In terms of purpose and orientation, spells and rituals can be differentiated. One is not better than the other, it is simply wise to know the difference.