There just isn't any comparison to make. If you want to see glaciers, go to a glacier (Hubbard, Malaspina, LeConte just to name a few). If you want to see a huge area (a bay, for example) that has many glaciers in or near the bay, go to Glacier Bay (although to do it justice, many feel you'll need days or weeks in Glacier Bay... it's really a HUGE area.) And, if you want to see a steep-walled, narrow fjord, go to Tracy Arm.
They're all quite different, and offer comepletely different opportunities for wildlife and ice viewing.
Oh, another difference is the best way to see each area.... Be sure to see Tracy Arm from a small boat, rather than a large ship, Glacier Bay can be experienced from most any size boat, and I don't think I'd sail to Hubbard Glacier on anything smaller than 500', unless I were in Yakutat for some reason already!