You cannot compare Svalbard and Alaska expedition cruises except for the cold weather. They are totally different. Think polar bears vs brown bears. Walrus and seals and otters. The Bering Sea. Dutch Harbor. Bear guards in Svalbard. Mountains and icebergs and pristine beauty. Landing on small islands where no human lives. Seeing the paw prints of a small animal and a large animal on the beach. Wildflowers of breathtaking beauty. Seabirds. Eagles.
Both cruises were exceptional. But know what you are getting into. Expedition cruising involves a commitment to getting up early, donning the outerwear, the boots etc. climbing into a zodiac, and then out of a zodiac, sometimes into the water (hence the boots). Going to the briefings to learn about the next days events. Being exhausted at night! In our opinion both were remarkable, once in a lifetime experiences.
I tried to upload some photos but the internet is not cooperating.
I cannot speak to the classic cruises for either location.