There is a difference between the nouns קדם and מזרח (east): The noun מזרח indicates the sunrise, while the noun קדם indicates that the direction is first in advantage or in place. And since the sun rises in the east, the east is called קדם.

And moreover the noun קדם is used to describe the eastern side of houses and cities, because in ancient times, their openings were to the east. Thus, in a place where it needs to clarify that the eastern side is first, it will say קדמה מזרחה (eastward, toward the sun-rising). And moreover, the noun קדם is not correct with respect to a house where there is no opening to the east.