Both are terrific options - it mainly comes down to brightness and battery size you're looking for:
Lumen Output: 250 Lumens vs 500 Lumens
Physical Size and Weight: 250 has a smaller footprint than 500
Battery Size: 3200 mAh vs 6400 mAh
Multicolor Mode: in AlpenGlow 250, MultiColor mode is two complementary colors sitting across from each other, each taking up a single panel. In AlpenGlow 500, Multicolor is a blend of three colors across the entire lantern
Price: AlpenGlow 250 is $59.95 | AlpenGlow 500 is $79.95