@primrosea, marquis and margrave nowadays basically are used interchangeably, a count-level noble who governs over highly important area, usually the borders or economic centres,
If I remember/understand correctly margrave title originated from Germanic Holy Roman Empire era while marquis from Frankish Carolingian Empire era, so historically they carry more cultural baggage than just that, but no one cares about it today,
Considering that, changing between margrave and marquis for no reason just makes it weird, it's like changing between count and earl.. oh, wait, they've done that...