To me they sound pretty much same if you’re very consciously saying the words as units, in isolation, “trying to pronounce them”.
If I say them a little more casually, though, the sounds that come out of my mouth are a little bit closer to “haam” and “hmster” - the vowel sound definitely gets emphasized in the former case and clipped almost entirely in the latter case.
It’s really easy to trick yourself into thinking you’re saying a word “properly” unless you’re very very conscious of the sounds you’re producing. As a Canadian, I know this - the stereotype Americans have of the Canadian accent is exaggerated, and it’s much stronger in rural areas, to the extent that I didn’t really think I sounded any different to the Americans in TV or movies. But Americans could still pretty quickly tell I was Canadian when I moved down there. The word “about” is one of the canonical tells, and although I don’t say “aboot” or anything, I learned that I do really say it in an accented way. It wouldn’t be apparent if you just asked me to pronounce the word, but in a sentence my mouth would gloss over the vowels, saying something more like “abut”.