If the Sun is in the same direction as the Moon the pull of the Sun and Moon are also in the same direction so the total pull is bigger and we get very high and very low tides. There is a big difference between high and low water. We call these ‘Spring’ tides although they may not be in the spring.
The ‘opposite’ of the Spring tides are the ‘Neap’ tides. These are tides where the difference between high and low water is not very great and are produced when the Sun and Moon are pulling on the water at right angles to each other.