Why are some names and numbers here different from 2 Samuel 8?

Chronicles tells the same battles as 2 Samuel 8, often in the same words, but not always. David "took Gath and its towns out of the hand of the Philistines" (18:1); 2 Samuel has "the bridle of the mother city" (2 Samuel 8:1). Where 2 Samuel 8:2 tells what was done to the Moabites after the battle, this chapter goes straight from "He defeated Moab" to "the Moabites became servants to David and brought tribute" (1 Chronicles 18:2). Here David took "one thousand chariots, seven thousand horsemen, and twenty thousand footmen" (1 Chronicles 18:4); there, "one thousand seven hundred horsemen and twenty thousand footmen" (2 Samuel 8:4). The bronze came "From Tibhath and from Cun" (1 Chronicles 18:8), or "From Betah and from Berothai" (2 Samuel 8:8). The king of Hamath is Tou, who sent "Hadoram his son" (1 Chronicles 18:10), or Toi, who sent "Joram his son" (2 Samuel 8:10). The nations the silver and gold came from begin "from Edom, from Moab" here (1 Chronicles 18:11) and "of Syria, of Moab" there (2 Samuel 8:12). The scribe is Shavsha (1 Chronicles 18:16) or Seraiah (2 Samuel 8:17), and the priest beside Zadok is "Abimelech the son of Abiathar" (1 Chronicles 18:16) or "Ahimelech the son of Abiathar" (2 Samuel 8:17); later this book has "Ahimelech the son of Abiathar" (1 Chronicles 24:6). 2 Samuel 8's honest questions set these side by side, and one of them asks how "Ahimelech the son of Abiathar" (2 Samuel 8:17) fits with "Abiathar the priest, the son of Ahimelech" (1 Samuel 30:7). The Bible gives the two accounts without explaining the differences, and this answer doesn't explain them or add up the numbers.