Galleria is a regular on my shopping circuit for the simple fact that my fiancee is Korea, I mean straight out of Seoul Korean (not Compton).
Everytime we go to Galleria my fiancee buys lots of meats, vegetables and sauces so I am assuming the market carries all of the Korean essentials. We are comparing it to the supermarket in the Koreatown downtown so it seems so big. We don't have experience going to the older one as we are new to Toronto. So on the Fiancee side BIG UPS.
Now for the picky white guys opinion which probably doesn't count for too much considering this place caters to the Korean pallet. I prefer the Kimchi at the supermarket downtown. I find the kimchi at Galleria to be too hot/spicy. Second the supermarket downtown in Christie carries a larger variety of Energy Drinks (also my favorite one from Japan) and Japanese snacks so I like to visit there. I only comment on this as me and my fiancee lived in Tokyo for 7 years so it is nice to be able to pick up a few of our favorite Japanese items while grabbing "her" Korean essentials. Yes that's right I said it, I did it, "her" Korean essentials. Just wish the Japanese stuff wasn't so overpriced!
Final Note - if you are new to Toronto and love Korean food, Galleria is definitely the place to go in the North York area.