There is a difference. My understand is that ö is pronounced more like the "i" sound in "girl" and the "ea" sound in "early" (I also think of how commentators pronounce the german soccer player özil :) ), whereas å is pronounced more like a long "o" as in "cold" or "bold". For reference, this is what I'm going off of: https://www.youtube.com/watch?v=G-JDHEIvxgQ
If you tell most of us Americans to pronounce Ö as in “learn” or “earl”, you will get a strong American “r” (we can’t help it). A better help (at least for us) to pronunciation of this vowel is to take the “e” sound of “men” and round your lips as for O. You’ll get a sound that doesn’t exist in our spoken English, but works! For example, try saying “Bread” the way you normally would, but round your lips as if you want to say “Brode”: you’ll get “Brӧd” (of course, your “r” should be flipped, but that’s really tough for some Americans!) “Shelled” with round lips gives you “Skӧld”, “smer” with round lips gives you “Smӧr”, etc.
The "common" and "neuter" genders in Swedish are grammatical genders, meaning that they do not correspond to whether the things being described are logically gender-neutral or not. Although a sandwich is an inanimate gender-neutral object, it still belongs to the "common" (en-words) gender in Swedish. It is best practice to memorize the grammatical gender of each noun as you go along.