Iggles vs Whiners will be a close game.
Generally speaking, home team gets +3 points in the calculations. So for the Niners to be favored against the Eagles by 2.5 in some places and 3 in others means that Vegas thinks the Niners are better than the Eagles by 5.5 to 6 points.
This is a HUGE game and potentially decides who gets the #1 seed in the NFC. This could be the conference championship right here.
Niners have an easier schedule, but have more losses than the Eagles. Niners win would knock the Eagles down a peg, and the easier Niners schedule gives them an opportunity to either have a better record, or with a tie, the Niners would have the tiebreaker.
Eagles have a tougher schedule, but less losses. They've had some quality wins in the last few weeks. A win against the Niners means they have a stranglehold on the #1 seed. They would hold most of the major tiebreakers with the Niners and Cowgirls. Especially if the Eagles go on to beat Arizona. Dallas already has losses to both Niners and Cardinals, so if the Eagles beat both of those teams, it's a wrap on at least the divisional crown, and most likely the #1 seed even if Dallas beats the Eagles in their next game.