When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as dramatically high and low. These are called neap tides. Tides vary from day to day. As the earth, moon, and sun orbit, their positions constantly shift, causing slightly different gravitational effects. This causes the tides to occur at slightly different times.
Tides also vary from place to place.
Geographical position determines the level of tide. In Northern California there are two unequal tides each day. In the Gulf of Mexico there is only one high tide and one low tide each day.