Leviticus 16:12-13 English Standard Version (ESV)

¹² And he shall take a censer full of coals of fire from the altar before the Lord, and two handfuls of sweet incense beaten small, and he shall bring it inside the veil ¹³ and put the incense on the fire before the Lord, that the cloud of the incense may cover the mercy seat that is over the testimony, so that he does not die. 

Before we get into the distinctions of the mercy seat please note that before the sprinkling of the blood sacrifice, incense is burnt in order to cover the mercy seat. The burning of the incense is symbolic of prayer.

Revelation 5:8 English Standard Version (ESV) And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and golden bowls full of incense, which are the prayers of the saints.

Within the ingredients for the incense there was pure frankincense which is one of the gifts of the Magi to the Christ child. It points towards Christ.

Now for the distinction of the mercy seat. This rite was only performed with the mercy seat placed upon the Art of the Covenant. No sacrificial blood would ever touch the ordinances of the covenant. The blood only fell on the mercy seat. The covering never allowed the blood to affect the covenant.

Numbers 7:89 English Standard Version (ESV) And when Moses went into the tent of meeting to speak with the Lord, he heard the voice speaking to him from above the mercy seat that was on the ark of the testimony, from between the two cherubim; and it spoke to him.

God speaks to us from a place of mercy. Who is it that speaks to us now from that place of mercy?

Hebrews 1:2a English Standard Version (ESV) but in these last days he has spoken to us by his Son