Here is the breakdown for the eyeshadows:
The dark brown in SG is much darker and more pigmented than AG.
The coral shades are both pigmented but SG's coral is lighter in color than AG.
The lighter brown in SG has more of a cool tone than AG.
The purples are both somewhat disappointing in their color pay off compared to the pan, but the purple in SG is more metallic and shimmery, while AG is a soft matte.
The bronze in SG has more of a golden brown tone, while AG is a true bronze color.
The light gold in SG is much more golden, while AG's light gold is a yellow gold and is much lighter.
The aqua shade in SG is more blue-based whereas AG's aqua is more green based, but I love my blue shadows and can appreciate their subtle differences.
The other two blues are a baby blue in SG and a darker teal in AG.
As far as I can tell, the two matte whites are the same.
The other oversized shadow in SG is a beige with a yellow undertone and that shade in AG is a shimmery light pink.
Honestly, I would not pick up both of them. They are very similar. If you like lighter colors, maybe go with SummerGlo, but other than that, I hope these pictures will help you decide. :) I love Lorac's eyeshadows, even though the purples in both of these palettes were quite the disappointment in pigmentation, the others are all wonderfully buttery and pretty darn perfect.
All pictures taken outside in natural daylight. Swatches are on dry skin with no primer, moisturizer, etc.
Thanks for reading!