I noticed in conjunctions there was another meaning for "utan" - "Jag älskar inte dig, utan honom", meaning "I don't love you, but (I do love) him." So, if I was to say something like, "Jag äter inte nötkött utan potatis", would that mean "I don't eat beef without potatoes" or, "I don't eat beef but (I do eat) potatoes"? Is the comma what makes the difference here?
"utan" means both "but this instead" and "without"; it's all about context.
• "I don't love you without him" doesn't make much sense, and should be "but I love him instead"; love is often mutually exclusive.
• Beef and potatoes aren't mutually exclusive, so you can eat beef with or without (med eller utan) potatoes, so "without" would make more sense.
Finally; it's also about intonation. Notice how you wrote a comma before "utan" in the first sentence. Putting emphasis on the final word (maybe a pause before "utan") does fall more into "but that instead".