In Leil Shabbat Kiddush we see the phrase:
תחילה למקראי קודש
Loose translation (mine): "The start of the holy callings (i.e. holy days)"
But in the Shabbat lunchtime somg Yom Ze Mechubad, we see the phrasing as:
ראשון הוא למקראי קודש
Loose translation (mine): "The first of the holy callings (i.e. holy days)"
Why is there a different word being used in each of these places? What is being conveyed in each of these places that might make that term more appropriate than the other?