I'll point them out as well using numbers yay.
1) The Maxx grill is all one piece, the SP23's grill has a cut line that lines up with the bonnet, the very lowest section stays in place.
2) The SP23 has round fog lamps and the Maxx oval. The SP23's bumper flows around the lamp and is rounded around the light, the Maxx's is sharp on the outer edges, and doesn't fit around the lamp, but has black filler plastic.
3) The SP23 has a larger lower air dam (taller) and also is more rounded, softer in appearance.
4) A feature line continuing from the headlamp is shorter on the SP23, softer and less pronounced, and doesn't reach the edge of the bumper. The Maxx's line reaches the edge of the bumper and gives a sharper appearance.
There you go.