@adriaan I'd see it as follow (over-simplified).
Option A. $594k outstanding (90% of $660k), monthly payment of $3742 (4564 - 1001 - 179) for 30y. Implied interest rate is 6.47%
Option B. $561k outstanding (85% of $660k), monthly payment of $3474 (4296 - 1001 -179), implied rate is 6.3%
A...